Associations between TOMM40 poly-T repeat variants and

dementia in cases with parkinsonism

Daniel Lindqvist, MD, PhD 1,2*, Inga Prokopenko PhD 3, Elisabet Londos, MD, PhD 4,5,

Lefkos Middleton, MD 3, Oskar Hansson, MD, PhD 4,5

1 Department of Clinical Sciences, Section for Psychiatry, Lund University, Lund,

Sweden 2 Psychiatry Skåne, Lund, Sweden 3 Neuroepidemiology and Ageing

Research, School of Public Health, Imperial College London, UK 4 Clinical Memory

Research Unit, Department of Clinical Sciences, Lund University, Malmö, Sweden

5Memory Clinic, Skåne University Hospital, Lund, Sweden.

* Correspondence to: Daniel Lindqvist, Department of Clinical Sciences, Section for

Psychiatry, Lund University, Lund, Sweden. Email: Daniel.Lindqvist@med.lu.se.

Adress: Baravägen 1, SE-221 85, Lund, Sweden; phone: +46-46 174474; fax: +46-

46-176048

Running title: TOMM40 poly-T repeat variants in PDD and DLB

1

Abstract

Background: Mitochondrial dysfunction has been implicated in the pathophysiology of

Parkinson’s disease (PD)-related pathologies.

Objective: To investigate the role of the Translocase of the Outer Mitochondrial

Membrane 40 homolog (TOMM40) variants in PD without dementia (PDND), PD with

dementia (PDD) and in Dementia with Lewy bodies (DLB).

Methods: 248 individuals, including 92 PDND, 55 PDD, and 101 DLB, were included.

The rs10524523 locus in the TOMM40 gene (TOMM40 poly-T repeat) is

characterized by a variable number of T residues that were classified into three

groups based on length; short (S), long (L), and very long (VL). We tested log-

additive genetic model of association with dementia and adjusted for age, sex, and

APOE ε4 carrier status. We analyzed cerebrospinal fluid (CSF) levels of Aβ42 and

Tau, biomarkers related to Alzheimer's disease (AD).

Results: PDD/DBL status and abnormal CSF AD biomarkers (Aβ42 and Aβ42/Tau ratio)

were both associated with the APOE ε4 allele (p<0.014) and the L allele of TOMM40

poly-T repeat (p<0.008). The VL allele was less frequently observed in the PDD/DLB

group (p=0.013). In APOE-ε4 adjusted analyses, the relationships between the L and

VL alleles and dementia status as well as CSF AD biomarkers were not significant.

When adjusting for APOE-ε4, however, there were associations between S carrier

status and PDD/DLB (p=0.019) and abnormal CSF levels of Aβ42/Tau ratio (p=0.037)

although these were not significant after adjustment for multiple comparisons.

2

Conclusion: Our results do not support the notion that TOMM40 poly-T repeat

variants have independent effects on PDD and DLB pathology. This relationship

seems to be driven by APOE-ε4.

Key words: PDD, DLB, TOMM40, APOE, Parkinson’s disease

3

Introduction

Alzheimer´s disease (AD), Parkinson´s disease (PD) and associated phenotypes

have been conceptualized as a complex continuum of late onset neurodegenerative

conditions potentially sharing common underlying pathophysiological mechanisms

[1]. The two PD associated dementia forms, Parkinson’s disease with dementia

(PDD) and Dementia with Lewy Bodies (DLB) share common clinical and

pathological findings, their main distinctive feature being the timing of dementia onset

with respect to the onset of motor parkinsonian signs [2].

Mitochondrial dysfunction has been implicated in the pathophysiology of AD- and PD-

related pathologies [3, 4]. The encoded product of the Translocase of the Outer

Mitochondrial Membrane 40 homolog (TOMM40) gene is involved in protein

transportation into mitochondria. The rs10524523 locus in the TOMM40 gene

(TOMM40 poly-T repeat) is characterized by a variable number of T residues that

have been classified into three groups, based on length; short (S), long (L), and very

long (VL) [5]. Adjacent to TOMM40 (on chromosome 19q13.2) is the apolipoprotein E

(APOE) gene, which encodes a protein known to play an important role in cholesterol

metabolism, in particular, in the central nervous system [6]. There are three APOE

allelic variants that have been well-described in the literature: APOE-ε2, APOE-ε3,

and APOE-ε4 [7]. APOE and TOMM40 are in linkage disequilibrium (LD); the APOE-

ε4 allele has been linked to the L allele of TOMM40 poly-T repeat and the APOE-ε3

allele has been linked to the S and VL alleles, whereas the APOE-ε2 allele has been

linked mostly to the S allele [5, 8]. Interestingly, a recent meta-analysis of genome-

wide association studies showed that both APOE and TOMM40 were associated with

4

general cognitive function in middle-aged and older adults [9].

It is now widely acknowledged that APOE-ε4 is a major risk factor for the non- familial

common late-onset form of AD. A meta-analysis has confirmed this and concluded

that the APOE-ε2/ε3 genotype may confer protection[10]. Studies on PD have shown

that APOE-ε2 might be a risk allele for PD, whereas the APOE-ε4 allele is associated

with increased risk for PDD [11, 12]. Contrarily, another large-scale study, did not

report a significant association between APOE and PD diagnosis, or between APOE

and MMSE scores within the PD group. In this study, however, the MMSE range was

26-30, thus the relationship between APOE and PD-related dementia was not tested

[13]. In a recent multi-center study, Bras et al. found that APOE is a strong genetic

risk factor also for DLB, and several SNPs associated with DLB were located within

the TOMM40 gene[14]. In a recently published review, Gottschalk et al., reported

unpublished data from a small case-control study and a post-mortem investigation in

support of an association between Lewy body pathology and TOMM40 poly-T repeat

[15].

Lower levels of β-amyloid42 (Aβ42) and higher levels of Tau in cerebrospinal fluid

(CSF) are strongly associated with presence of Aβ-containing neuritic plaques and

tau-containing neurofibrillary tangles, respectively, in subjects with AD [16, 17].

Carrier status of the APOE-ε4 allele has been associated with lower CSF Aβ4 levels

in elderly controls and in cases with AD, although the association with CSF Tau is

less robust [18]. The relationship between APOE genotype and CSF Aβ42 and Tau

has been less studied in patients with PD-related disorders, but there is evidence that

PD subjects with the APOE-ε4 allele exhibit lower CSF Aβ42 levels [19]. There are yet

5

few studies evaluating the relationship between TOMM40 poly-T repeat and CSF AD

biomarkers. Cruchaga and colleagues found a strong association between TOMM40

poly T repeat and CSF Aβ42 levels in subjects with AD, although this association was

not significant when APOE genotype was added as a covariate in the model [20].

Alpha-synuclein is a protein that contribute to the pathophysiology of PD-related

conditions such as DLB [21], and some experimental studies suggest that it might

also be involved in mitochondrial dysfunction [15, 22].

No previously published studies have investigated TOMM40 common genetic

variants in PDD or DLB. Peplonska et al. did not find any associations between PD

risk and TOMM40 genotype or allele frequencies, but did not investigate specific

effects on PDD or DLB [23]. Even though previous studies have shown that the

APOE-ε4 allele is associated with AD, as well as PDD and DLB, the role of TOMM40

common genetic variants in PDD and DLB is yet to be elucidated. In this study, we

aimed at testing the relationship between DLB/PDD and allelic variants of TOMM40

poly-T repeat and whether these associations are independent of APOE-ε4 allele

carrier status or not. Moreover, we wanted to test the relationship betweenTOMM40

poly-T repeat and CSF levels of Aβ42 and Aβ42/Tau ratio, once again adjusting for

APOE-ε4 allele carrier status.

Materials and methods

Ethical considerations

6

The Ethics Committee of Lund University approved this study. Study participants

gave informed consent to research. The study was conducted in accordance with the

provisions of the Helsinki Declaration.

Study participants

Between 2008 and 2012, 248 subjects (89 women and 159 men, mean age 72±5

years) were recruited at the Neurology Clinic and the Memory Clinic at the Skåne

University Hospital in Lund/Malmö, Sweden. Ninety-two were diagnosed with PD - no

dementia (PDND), 55 with PDD and 101 with DLB. PD diagnosis was verified

according to the NINDS Diagnostic Criteria [24]. A diagnosis of PDD was determined

according to the Clinical Diagnostic Criteria for Dementia Associated with PD [25]. A

diagnosis of probable DLB was made according to the DLB consensus criteria [2].

Genotyping

APOE genotypes were determined by genotyping the two haplotype tagging SNPs

rs429358 (hg19 chr19:g.4541194T>C) and rs7412 (hg19 chr19:45412079C>T),

whose combination uniquely identifies the ε2/ε3/ε4 haplotypes, with rs429358 T-allele

and rs7412 C-allele indicating APOE-ε3, rs429358 T and rs7412 T indicating APOE-

ε2 and rs429358 C and rs7412 C indicating APOE-ε4. APOE genotype was missing

for one PDD/DLB subject. The TOMM40 poly T repeat rs10524523 (hg19

chr19:45403049-45403067-> polyT) was genotyped directly through PCR, obtaining

a direct read of the poly T length, which were then thus grouped as follows: length of

fewer than 20 thymine bases was classified as Short (S), length in range 20 to 30

bases was classified as Long (L) and length of 31 or more bases was classified as

7

Very Long (VL) [26]. The distinction between the L and VL alleles of TOMM40 poly-T

repeat has varied across previous studies, with some defining the L allele as <31 [26,

27] and other as <30 [28]. As noted by Roses et al. [8], this decision may be guided

by APOE genotype since the TOMM40 L allele is almost without exception linked to

the APOE-ε4 allele in whites. In our sample, all subjects with a poly T length of 30 (6

PDD/DLB subjects and 2 PDND subjects) were APOE-ε4 carriers, thus supporting

our classification of the L allele of TOMM40 poly-T repeat >31. In addition to this

approach, we also classified TOMM40 poly-T alleles based on tertiles, and re-tested

the relationship between dementia status and TOMM40 poly-T alleles using this

classification (see supplementary information). Genotyping was carried out by

Polymorphic DNA, Alameda, California, using standard PCR procedures.

CSF Samples

CSF levels of Aβ42, alpha-synuclein, and Tau were measured in CSF samples

obtained from 115 subjects (36 PDD/DLB subjects and 79 PDND subjects). Lumbar

punctures were performed between 11 am and 1 pm in the L3/L4 or L4/L5 interspace

with the patient sitting and non-fasting. The samples were collected in polypropylene

tubes and gently mixed to avoid gradient effects. All samples were centrifuged within

30 minutes at +4°C at 2000g for 10 min to remove cells and debris, and then stored

in aliquots at −80°C pending biochemical analysis. The CSF levels of Aβ42 and Tau

were quantified using EUROIMMUN Beta-amyloid1-42 ELISA and EUROIMMUN Total

Tau ELISA. CSF alpha-synuclein was analyzed with luminex assays as previously

described [29].

8

Statistical analyses

The Statistical Package for the Social Sciences (SPSS) was used for statistical

analyses. Student´s T-tests were used for group-wise comparisons. Aβ42 levels and

the Aβ42/Tau ratio were normally distributed, hence raw data was used. Pearson’s

chi-square test was used to compare proportions. Logistic regression was used to

analyze binary outcome, having PDD/DLB status as dependent variable, and allelic

variants of TOMM40 poly-T repeat as independent variables. Linear regression

models were used to test the relationship between CSF levels of Aβ42 and Tau

(dependent variable) and allelic variants of TOMM40 poly-T repeat (independent

variables). Regression models were adjusted for age, sex and APOE-ε4 allele carrier

status.

Given that we did three separate analyses (S, L, and VL allelic variants versus

PDD/DLB status, Aβ42 levels and Aβ42/Tau), p-values of <0.017 (0.05/3) were

considered significant. All tests were two-sided.

Results

Demographic characteristics

The demographics of the PDD/DLB and PDND subjects are given in Table 1. Groups

differed significantly with regards to age and CSF levels of CSF Aβ42 and Aβ42/Tau,

but not with regards to disease duration and sex distribution. The L allele of TOMM40

poly-T repeat was strongly correlated with APOE-ε4, i.e. 99% of those with the L

allele also carried the APOE-ε4 allele. APOE-ε4 allele carriers had significantly lower

levels CSF Aβ42 (P-value<0.001, t=6.6) and Aβ42/Tau (P-value<0.001, t=7.3) than

non-carriers.

9

Associations between the APOE4 allele and PDD/DLB status

Forty-six % of the PDD/DLB subjects were APOE-ε4 carriers compared to 28 % of

the PDND subjects (P-value=0.014, odds ratio (OR)=2.26, 95% confidence interval

(CI)=1.18-4.34).

Associations between allelic variants of TOMM40 poly-T repeat and PDD/DLB status

The distribution of TOMM40 poly-T alleles in the non-demented PD patients

compared to the PDD/DLB group is given in Table 2 (adjusted for age and sex). In

our series, 48% of the subjects with PDD or DLB were L carriers compared to 28% of

the PDND subjects (P-value=0.007, OR=2.43, 95% CI=1.27-4.65). Contrarily, the VL

allele was less frequently observed in the PDD/DLB group compared to PDND

subjects (P-value=0.013, OR=0.44, 95% CI=0.23-0.84). When adjusting for APOE4

allele carrier status these changes were no longer significant at the level of p<0.017,

however, there was a trend for an association between the TOMM40 poly-T S allele

and PDD/DLB status (Table 2). The main analyses were also performed with

TOMM40 poly-T alleles determined based on tertiles, and results were very similar

(see supplementary material).

To increase the likelihood that the non-demented PD sample actually represented a

“non-demented endophenotype” (as opposed to non-demented PD subjects that

would later on convert to PDD) we re-performed these group comparisons including

only those non-demented PD subjects with disease duration >5 years (n=61). In

these sub-analyses adjusting for age and sex, PDD/DLB subjects were more likely to

be TOMM40 poly-T L allele carriers (P-value=0.003, OR=3.23, 95% CI=1.51-6.92),

10

although the difference in distribution of VL (P-value=0.061, OR=0.51, 95% CI=0.25-

1.03), and S (P-value=0.535, OR=1.27, 95% CI=0.60-2.72) allele carrier status did

not differ significantly between groups.

Again, when we additionally adjusted for APOE-ε4 carrier status, the relationship

between PDD/DLB status and TOMM40 poly-T L allele carrier status was no longer

significant when comparing PDD/DLB subjects and those PDND subjects with

disease duration of more than 5 years (P-value>0.05).

Associations between allelic variants of TOMM40 poly-T repeat and CSF levels of

Aβ42 and Tau

In order to test whether the associations between allelic variants of TOMM40 poly-T

repeat and dementia in PD might be mediated via increased AD-related pathology

we also measured CSF levels of Aβ42, and tau in a subpopulation (n=115).

Associations between allelic variants of TOMM40 poly-T repeat and CSF Aβ42 and

Aβ42/Tau were tested using linear regression models in all subjects and in PDND

subjects only, adjusted for age and sex. Results are summarized in Table 3

(supplementary material). CSF levels of Aβ42 and Tau per genotype group are shown

in Figures 1 and 2 (in all subjects and in PDND subjects only).

L allele carrier status was significantly associated with lower Aβ42 (all subjects: P-

value<0.001, β=-0.49; PDND subjects only: P-value<0.001, β=-0.56), and lower

Aβ42/Tau (all subjects: P-value<0.001, β=-0.49; PDND subjects only: P-value<0.001,

β=-0.49). In all subjects, but not in PDND only, VL allele carrier status was

associated with higher Aβ42 (all subjects: P-value=0.006, β=0.25; PDND subjects

11

only: P-value=0.090, β=0.19), as well as higher Aβ42/Tau (all subjects: P-

value=0.019, β=0.20; PDND subjects only: P-value=0.120, β=0.17).

When additionally adjusting for APOE4 allele carrier status these changes were no

longer significant at the level of p<0.017, however, there was a trend for an

association between the TOMM40 poly-T S allele and CSF Aβ42/Tau (Table 4,

supplementary material). These analyses were also performed with TOMM40 poly-T

alleles determined based on tertiles, and results were very similar (see

supplementary material).

In all subjects (or in PDND subjects only), there were no significant association

between CSF alpha-syn and TOMM40 poly-T alleles or between CSF alpha-syn and

APOE4 (all p>0.18).

Discussion

We here show, in a clinical sample of PD (with and without dementia) and DLB, that

those with dementia were more likely to carry the L allele of TOMM40 poly-T repeat.

Moreover, we show that the L allele of TOMM40 poly-T repeat is associated with

lower Aβ42 and Aβ42/Tau levels in CSF, indicating possible presence of AD-related

pathology. Interestingly this association was also observed in PDND subjects.

PDD/DLB patients were more likely to carry the APOE-ε4 allele, and this allelic

variant was strongly inter-correlated with the L allele. When the sample was re-

analyzed additionally adjusting for APOE-ε4 allele carrier status, the associations

between the L allele and PDD/DLB status as well as CSF biomarker levels did not

remain significant, suggesting that APOE-ε4 allele carrier status may have driven the

12

results. However, when we adjusted for APOE-ε4 carrier-status, we observed

nominally significant associations between the S allele of TOMM40 poly-T repeat

and DLB/PDD status as well as lower CSF levels of CSF Aβ42/Tau, although these

did not reach statistical significance adjustment for multiple comparisons. Our

findings suggest that there may be an effect of TOMM40 on PDD/DLB and AD-

related pathology that is independent of APOE-ε4, although this needs to be

replicated in independent cohorts.

We replicate previous studies of a link between APOE-ε4 allele and PDD/DLB [30,

31], but also show an association between TOMM40 allelic variants and PDD/DLB.

The TOMM40 gene product plays an important role in mitochondrial function, which

is key to almost all aspects of cellular metabolism [15]. The TOMM complex is the

main entry portal for proteins synthesized in the cytoplasm to enter the mitochondria,

and TOMM40 is the key subunit of this protein transport complex [15]. Results from

genetic knock-out studies have emphasized the importance ofTOMM40 for the

viability of eukaryotic organisms [32, 33]. TOMM40 and APOE are both located on

chromosome 19 in the tight gene cluster TOMM40-APOE-APOC1-APOC4-APOC2

that forms a strong LD block [34]. Late-onset Alzheimer´s disease (LOAD) has been

strongly associated with the APOE LD region (specifically the APOE-ε4 haplotype)

[35, 36]. However, other genetic factors within this LD block may also be linked to

cognitive decline. As reviewed by Gottschalk et al., several studies have found that

TOMM40 SNPs are associated with LOAD [15] and there is evidence that this effect

may be independent of APOE [37].

There are only a few previous studies investigating the relationship between

13

TOMM40 and PDD/DLB. In a large-scale association study of 54 genomic region

previously implicated in PD or AD, Bras et al. found several SNPs associated with

DLB located within the TOMM40 gene [38]. There are also unpublished clinical and

post-mortem data recently reported in a review by Gottschalk et al. supporting the

link between DLB and the TOMM40 gene [15]. Moreover, TOMM40 polymorphisms

have been shown to predict cerebrospinal fluid levels of apoE in non-demented

individuals [39] and APOE expression in the AD brain [40]. APOE-ε4 may also be

involved in mitochondrial dysfunction and neurotoxicity, which are potential

pathophysiological mechanisms underlying dementia and PD [3, 4, 41]. Indeed,

some authors have speculated that changes in APOE expression is a secondary

consequence, and that TOMM40 variants affecting mitochondrial function are the

actual primary effecters for AD risk [40]. In line with this notion and partly in line with

our own findings, Roses et al. showed the L allele of TOMM40 poly-T repeat is most

commonly linked with APOE-ε4, and that the longer length of the allele of TOMM40

poly-T repeat was associated with a higher risk for late-onset AD [5]. However,

several studies have failed to show an independent effect of TOMM40 on AD-related

pathology and cognitive decline. Cruchaga et al. found an association between

TOMM40 poly T repeat and low CSF Aβ42 levels in AD, although this was no longer

significant after taking into account the effects of APOE [20]. Similarly, Jun et al. did

not find a significant association between TOMM40 and AD risk or age of onset after

adjusting for APOE genotype [42]. In line with these studies, we found that APOE

and TOMM40 shared a significant amount of variance, and the association between

dementia and L allele was no longer significant after taking APOE-ε4 into account.

Few studies have investigated TOMM40 genetic variants in relation to PD. Peplonska

14

et al. found no significant difference in the distribution of TOMM40 poly-T alleles or

APOE genotypes between 407 PD subjects and 305 healthy controls [23]. However,

the authors did not specify the exact number of dementia cases in their sample, but

noted that it was low and that this may have been one of the reasons for their

negative findings [23]. Based on our findings, we hypothesize that TOMM40-L may

be more strongly associated with dementia in PD rather than PD per se. In support of

a link between the TOMM40 L allele and dementia, Maruszak et al. showed that the

L allele of TOMM40 poly-T repeat was significantly associated with LOAD compared

to controls, even though the APOE ε4 remains the strongest risk factor for LOAD

[27].

The mechanisms behind the association between dementia in PD and APOE-ε4

and/or the L allele of TOMM40 poly-T repeat are not yet fully understood.

Consequently, we quantified the CSF levels of Aβ42 and Tau in a subpopulation of the

study participants. Decreased CSF Aβ42 is an independent marker of cerebral

accumulation of Aβ fibrils, and increased CSF tau is a marker of tau-pathology and

neurodegeneration [18]. In the present study we found that the L allele of TOMM40

poly-T repeat was associated both with lower CSF-Aβ42 and Aβ42/Tau in PD,

suggesting that the increased risk of dementia in PD associated with these

genotypes is mediated via possible induction of AD-related pathologies. Once again,

these findings did not remain significant after adjusting for APOE-ε4 carrier status,

thus this latter known risk factor for AD-related pathology may have been driving

these correlations. While these associations have not been tested, to the best of our

knowledge, in PDD/DLB specifically, our findings are generally in line with studies on

AD dementia [18], [43], [20].

15

As this is cross-sectional study, our findings do not infer causality. Furthermore, in

the absence of a healthy control group, our data cannot establish whether the

distributions of TOMM40 poly-T repeat variants differ between PD patients and

healthy controls. . Also, this is one of the first studies exploring the association

between TOMM40 and PDD and DLB. Therefore our results should be considered as

preliminary and need to be replicated in an independent sample. Moreover, this is the

first study to simultaneously investigate CSF biomarkers and APOE or TOMM40

genetic variants in a clinical PDD/DLB sample. A potential limitation of the present

investigation is that it comprised a smaller sample size compared to some other

previously published studies in the field [23, 27, 28]. Our study did, however, have

some distinct advantages in the thorough clinical characterization of subjects,

including CSF data. The latter feature may provide important clues in interpreting the

genetic data. Moreover, we are the first to investigate TOMM40 in PDD/DLB versus

non-demented PD subjects. In light of this, we believe that our study is important in

formulating new hypotheses regarding TOMM40 versus PDD/DLB that should be

confirmed, or refuted, in future larger trials.

In conclusion, our investigation suggests that the L allele of TOMM40 poly-T repeat

(a gene involved in mitochondrial function) is more common in PDD/DLB subjects

than in non-demented PD. Based on our results, these findings may, however, be

accounted for by an increased frequency of APOE ε4 in the PDD/DLB group. The link

between dementia in PD and the L allele ofTOMM40 poly-T repeat and/or APOE ε4

alleles seem to be mediated via Aβ and Tau pathology. However, the associations

between the S allele of TOMM40 poly-T repeat and PDD/DLB status and abnormal

16

CSF Aβ42/Tau levels need to be replicated in independent patient cohorts.

Acknowledgements

Helene Jacobsson is acknowledged for statistical advice. The study was supported

by the Swedish Research Council, The Parkinson Foundation of Sweden, the

European Research Council, the Crafoord Foundation, the Swedish Brain

Foundation, the Swedish Federal Government under the ALF Agreement, Multipark,

and the Knut and Alice Wallenberg Foundation. The Imperial College London

investigators were supported by grants from Parkinson’s UK, the Michael J Fox

Foundation and UCB. The funding sources had no role in the design and conduct of

the study; in the collection, analysis, interpretation of the data; or in the preparation,

review, or approval of the manuscript.

Conflict of Interest

Each of the authors declares no conflict of interest in the work reported.

17

References

[1] Sutherland GT, Siebert GA, Kril JJ, Mellick GD (2011) Knowing me, knowing you:

can a knowledge of risk factors for Alzheimer's disease prove useful in

understanding the pathogenesis of Parkinson's disease? J Alzheimers Dis 25, 395-

415.

[2] McKeith IG, Dickson DW, Lowe J, Emre M, O'Brien JT, Feldman H, Cummings J,

Duda JE, Lippa C, Perry EK, Aarsland D, Arai H, Ballard CG, Boeve B, Burn DJ,

Costa D, Del Ser T, Dubois B, Galasko D, Gauthier S, Goetz CG, Gomez-Tortosa E,

Halliday G, Hansen LA, Hardy J, Iwatsubo T, Kalaria RN, Kaufer D, Kenny RA,

Korczyn A, Kosaka K, Lee VM, Lees A, Litvan I, Londos E, Lopez OL, Minoshima S,

Mizuno Y, Molina JA, Mukaetova-Ladinska EB, Pasquier F, Perry RH, Schulz JB,

Trojanowski JQ, Yamada M, Consortium on DLB (2005) Diagnosis and

management of dementia with Lewy bodies: third report of the DLB Consortium.

Neurology 65, 1863-1872.

[3] Swerdlow RH, Khan SM (2004) A "mitochondrial cascade hypothesis" for

sporadic Alzheimer's disease. Med Hypotheses 63, 8-20.

[4] Subramaniam SR, Chesselet MF (2013) Mitochondrial dysfunction and oxidative

stress in Parkinson's disease. Prog Neurobiol 106-107, 17-32.

[5] Roses AD, Lutz MW, Amrine-Madsen H, Saunders AM, Crenshaw DG, Sundseth SS,

Huentelman MJ, Welsh-Bohmer KA, Reiman EM (2010) A TOMM40 variable-

length polymorphism predicts the age of late-onset Alzheimer's disease.

Pharmacogenomics J 10, 375-384.

18

[6] Bu G (2009) Apolipoprotein E and its receptors in Alzheimer's disease: pathways,

pathogenesis and therapy. Nat Rev Neurosci 10, 333-344.

[7] Siest G, Pillot T, Regis-Bailly A, Leininger-Muller B, Steinmetz J, Galteau MM,

Visvikis S (1995) Apolipoprotein E: an important gene and protein to follow in

laboratory medicine. Clin Chem 41, 1068-1086.

[8] Roses AD, Lutz MW, Crenshaw DG, Grossman I, Saunders AM, Gottschalk WK

(2013) TOMM40 and APOE: Requirements for replication studies of association

with age of disease onset and enrichment of a clinical trial. Alzheimers Dement 9,

132-136.

[9] Davies G, Armstrong N, Bis JC, Bressler J, Chouraki V, Giddaluru S, Hofer E,

Ibrahim-Verbaas CA, Kirin M, Lahti J, van der Lee SJ, Le Hellard S, Liu T, Marioni

RE, Oldmeadow C, Postmus I, Smith AV, Smith JA, Thalamuthu A, Thomson R,

Vitart V, Wang J, Yu L, Zgaga L, Zhao W, Boxall R, Harris SE, Hill WD, Liewald DC,

Luciano M, Adams H, Ames D, Amin N, Amouyel P, Assareh AA, Au R, Becker JT,

Beiser A, Berr C, Bertram L, Boerwinkle E, Buckley BM, Campbell H, Corley J, De

Jager PL, Dufouil C, Eriksson JG, Espeseth T, Faul JD, Ford I, Scotland G, Gottesman

RF, Griswold ME, Gudnason V, Harris TB, Heiss G, Hofman A, Holliday EG,

Huffman J, Kardia SL, Kochan N, Knopman DS, Kwok JB, Lambert JC, Lee T, Li G, Li

SC, Loitfelder M, Lopez OL, Lundervold AJ, Lundqvist A, Mather KA, Mirza SS,

Nyberg L, Oostra BA, Palotie A, Papenberg G, Pattie A, Petrovic K, Polasek O, Psaty

BM, Redmond P, Reppermund S, Rotter JI, Schmidt H, Schuur M, Schofield PW,

Scott RJ, Steen VM, Stott DJ, van Swieten JC, Taylor KD, Trollor J, Trompet S,

Uitterlinden AG, Weinstein G, Widen E, Windham BG, Jukema JW, Wright AF,

Wright MJ, Yang Q, Amieva H, Attia JR, Bennett DA, Brodaty H, de Craen AJ,

Hayward C, Ikram MA, Lindenberger U, Nilsson LG, Porteous DJ, Raikkonen K,

Reinvang I, Rudan I, Sachdev PS, Schmidt R, Schofield PR, Srikanth V, Starr JM,

Turner ST, Weir DR, Wilson JF, van Duijn C, Launer L, Fitzpatrick AL, Seshadri S,

Mosley TH, Jr., Deary IJ (2015) Genetic contributions to variation in general

cognitive function: a meta-analysis of genome-wide association studies in the

CHARGE consortium (N=53 949). Mol Psychiatry 20, 183-192.

19

[10] Farrer LA, Cupples LA, Haines JL, Hyman B, Kukull WA, Mayeux R, Myers RH,

Pericak-Vance MA, Risch N, van Duijn CM (1997) Effects of age, sex, and ethnicity

on the association between apolipoprotein E genotype and Alzheimer disease. A

meta-analysis. APOE and Alzheimer Disease Meta Analysis Consortium. JAMA

278, 1349-1356.

[11] Huang X, Chen P, Kaufer DI, Troster AI, Poole C (2006) Apolipoprotein E and

dementia in Parkinson disease: a meta-analysis. Arch Neurol 63, 189-193.

[12] Huang X, Chen PC, Poole C (2004) APOE-[epsilon]2 allele associated with higher

prevalence of sporadic Parkinson disease. Neurology 62, 2198-2202.

[13] Federoff M, Jimenez-Rolando B, Nalls MA, Singleton AB (2012) A large study

reveals no association between APOE and Parkinson's disease. Neurobiol Dis 46,

389-392.

[14] Bras J, Guerreiro R, Darwent L, Parkkinen L, Ansorge O, Escott-Price V, Hernandez

DG, Nalls MA, Clark LN, Honig LS, Marder K, Van Der Flier WM, Lemstra A,

Scheltens P, Rogaeva E, St George-Hyslop P, Londos E, Zetterberg H, Ortega-

Cubero S, Pastor P, Ferman TJ, Graff-Radford NR, Ross OA, Barber I, Braae A,

Brown K, Morgan K, Maetzler W, Berg D, Troakes C, Al-Sarraj S, Lashley T, Compta

Y, Revesz T, Lees A, Cairns N, Halliday GM, Mann D, Pickering-Brown S, Dickson

DW, Singleton A, Hardy J (2014) Genetic analysis implicates APOE, SNCA and

suggests lysosomal dysfunction in the etiology of dementia with Lewy bodies.

Hum Mol Genet.

[15] Gottschalk WK, Lutz MW, He YT, Saunders AM, Burns DK, Roses AD, Chiba-Falek

O (2014) The Broad Impact of TOM40 on Neurodegenerative Diseases in Aging. J

Parkinsons Dis Alzheimers Dis 1.

[16] Vanmechelen E, Vanderstichele H, Hulstaert F, Andreasen N, Minthon L, Winblad

B, Davidsson P, Blennow K (2001) Cerebrospinal fluid tau and beta-amyloid(1-

42) in dementia disorders. Mech Ageing Dev 122, 2005-2011.

20

[17] Blennow K, Mattsson N, Scholl M, Hansson O, Zetterberg H (2015) Amyloid

biomarkers in Alzheimer's disease. Trends Pharmacol Sci 36, 297-309.

[18] Lautner R, Palmqvist S, Mattsson N, Andreasson U, Wallin A, Palsson E, Jakobsson

J, Herukka SK, Owenius R, Olsson B, Hampel H, Rujescu D, Ewers M, Landen M,

Minthon L, Blennow K, Zetterberg H, Hansson O, Alzheimer's Disease

Neuroimaging I (2014) Apolipoprotein E genotype and the diagnostic accuracy of

cerebrospinal fluid biomarkers for Alzheimer disease. JAMA Psychiatry 71, 1183-

1191.

[19] Zhang J, Mattison HA, Liu C, Ginghina C, Auinger P, McDermott MP, Stewart T,

Kang UJ, Parkinson Study Group DI, Cain KC, Shi M (2013) Longitudinal

assessment of tau and amyloid beta in cerebrospinal fluid of Parkinson disease.

Acta Neuropathol 126, 671-682.

[20] Cruchaga C, Nowotny P, Kauwe JS, Ridge PG, Mayo K, Bertelsen S, Hinrichs A,

Fagan AM, Holtzman DM, Morris JC, Goate AM, Alzheimer's Disease Neuroimaging

I (2011) Association and expression analyses with single-nucleotide

polymorphisms in TOMM40 in Alzheimer disease. Arch Neurol 68, 1013-1019.

[21] Lee HJ, Bae EJ, Lee SJ (2014) Extracellular alpha--synuclein-a novel and crucial

factor in Lewy body diseases. Nat Rev Neurol 10, 92-98.

[22] Bender A, Desplats P, Spencer B, Rockenstein E, Adame A, Elstner M, Laub C,

Mueller S, Koob AO, Mante M, Pham E, Klopstock T, Masliah E (2013) TOM40

mediates mitochondrial dysfunction induced by alpha-synuclein accumulation in

Parkinson's disease. PLoS One 8, e62277.

[23] Peplonska B, Safranow K, Gaweda-Walerych K, Maruszak A, Czyzewski K,

Rudzinska M, Barcikowska M, Zekanowski C (2013) TOMM40 and APOE common

genetic variants are not Parkinson's disease risk factors. Neurobiol Aging 34,

2078 e2071-2072.

21

[24] Gelb DJ, Oliver E, Gilman S (1999) Diagnostic criteria for Parkinson disease. Arch

Neurol 56, 33-39.

[25] Emre M, Aarsland D, Brown R, Burn DJ, Duyckaerts C, Mizuno Y, Broe GA,

Cummings J, Dickson DW, Gauthier S, Goldman J, Goetz C, Korczyn A, Lees A, Levy

R, Litvan I, McKeith I, Olanow W, Poewe W, Quinn N, Sampaio C, Tolosa E, Dubois

B (2007) Clinical diagnostic criteria for dementia associated with Parkinson's

disease. Mov Disord 22, 1689-1707; quiz 1837.

[26] Lutz MW, Crenshaw DG, Saunders AM, Roses AD (2010) Genetic variation at a

single locus and age of onset for Alzheimer's disease. Alzheimers Dement 6, 125-

131.

[27] Maruszak A, Peplonska B, Safranow K, Chodakowska-Zebrowska M, Barcikowska

M, Zekanowski C (2012) TOMM40 rs10524523 polymorphism's role in late-onset

Alzheimer's disease and in longevity. J Alzheimers Dis 28, 309-322.

[28] Lyall DM, Harris SE, Bastin ME, Munoz Maniega S, Murray C, Lutz MW, Saunders

AM, Roses AD, Valdes Hernandez Mdel C, Royle NA, Starr JM, Porteous DJ,

Wardlaw JM, Deary IJ (2014) Are APOE varepsilon genotype and TOMM40 poly-T

repeat length associations with cognitive ageing mediated by brain white matter

tract integrity? Transl Psychiatry 4, e449.

[29] Hall S, Ohrfelt A, Constantinescu R, Andreasson U, Surova Y, Bostrom F, Nilsson C,

Hakan W, Decraemer H, Nagga K, Minthon L, Londos E, Vanmechelen E, Holmberg

B, Zetterberg H, Blennow K, Hansson O (2012) Accuracy of a panel of 5

cerebrospinal fluid biomarkers in the differential diagnosis of patients with

dementia and/or parkinsonian disorders. Arch Neurol 69, 1445-1452.

[30] Tsuang D, Leverenz JB, Lopez OL, Hamilton RL, Bennett DA, Schneider JA,

Buchman AS, Larson EB, Crane PK, Kaye JA, Kramer P, Woltjer R, Trojanowski JQ,

Weintraub D, Chen-Plotkin AS, Irwin DJ, Rick J, Schellenberg GD, Watson GS,

Kukull W, Nelson PT, Jicha GA, Neltner JH, Galasko D, Masliah E, Quinn JF, Chung

KA, Yearout D, Mata IF, Wan JY, Edwards KL, Montine TJ, Zabetian CP (2013)

22

APOE epsilon4 increases risk for dementia in pure synucleinopathies. JAMA

Neurol 70, 223-228.

[31] Williams-Gray CH, Goris A, Saiki M, Foltynie T, Compston DA, Sawcer SJ, Barker

RA (2009) Apolipoprotein E genotype as a risk factor for susceptibility to and

dementia in Parkinson's disease. J Neurol 256, 493-498.

[32] Baker KP, Schaniel A, Vestweber D, Schatz G (1990) A yeast mitochondrial outer

membrane protein essential for protein import and cell viability. Nature 348,

605-609.

[33] Taylor RD, McHale BJ, Nargang FE (2003) Characterization of Neurospora crassa

Tom40-deficient mutants and effect of specific mutations on Tom40 assembly. J

Biol Chem 278, 765-775.

[34] Roses AD (2006) On the discovery of the genetic association of Apolipoprotein E

genotypes and common late-onset Alzheimer disease. J Alzheimers Dis 9, 361-

366.

[35] Harold D, Abraham R, Hollingworth P, Sims R, Gerrish A, Hamshere ML, Pahwa JS,

Moskvina V, Dowzell K, Williams A, Jones N, Thomas C, Stretton A, Morgan AR,

Lovestone S, Powell J, Proitsi P, Lupton MK, Brayne C, Rubinsztein DC, Gill M,

Lawlor B, Lynch A, Morgan K, Brown KS, Passmore PA, Craig D, McGuinness B,

Todd S, Holmes C, Mann D, Smith AD, Love S, Kehoe PG, Hardy J, Mead S, Fox N,

Rossor M, Collinge J, Maier W, Jessen F, Schurmann B, Heun R, van den Bussche H,

Heuser I, Kornhuber J, Wiltfang J, Dichgans M, Frolich L, Hampel H, Hull M,

Rujescu D, Goate AM, Kauwe JS, Cruchaga C, Nowotny P, Morris JC, Mayo K,

Sleegers K, Bettens K, Engelborghs S, De Deyn PP, Van Broeckhoven C, Livingston

G, Bass NJ, Gurling H, McQuillin A, Gwilliam R, Deloukas P, Al-Chalabi A, Shaw CE,

Tsolaki M, Singleton AB, Guerreiro R, Muhleisen TW, Nothen MM, Moebus S,

Jockel KH, Klopp N, Wichmann HE, Carrasquillo MM, Pankratz VS, Younkin SG,

Holmans PA, O'Donovan M, Owen MJ, Williams J (2009) Genome-wide association

study identifies variants at CLU and PICALM associated with Alzheimer's disease.

Nat Genet 41, 1088-1093.

23

[36] Lambert JC, Heath S, Even G, Campion D, Sleegers K, Hiltunen M, Combarros O,

Zelenika D, Bullido MJ, Tavernier B, Letenneur L, Bettens K, Berr C, Pasquier F,

Fievet N, Barberger-Gateau P, Engelborghs S, De Deyn P, Mateo I, Franck A,

Helisalmi S, Porcellini E, Hanon O, European Alzheimer's Disease Initiative I, de

Pancorbo MM, Lendon C, Dufouil C, Jaillard C, Leveillard T, Alvarez V, Bosco P,

Mancuso M, Panza F, Nacmias B, Bossu P, Piccardi P, Annoni G, Seripa D,

Galimberti D, Hannequin D, Licastro F, Soininen H, Ritchie K, Blanche H, Dartigues

JF, Tzourio C, Gut I, Van Broeckhoven C, Alperovitch A, Lathrop M, Amouyel P

(2009) Genome-wide association study identifies variants at CLU and CR1

associated with Alzheimer's disease. Nat Genet 41, 1094-1099.

[37] Omoumi A, Fok A, Greenwood T, Sadovnick AD, Feldman HH, Hsiung GY (2014)

Evaluation of late-onset Alzheimer disease genetic susceptibility risks in a

Canadian population. Neurobiol Aging 35, 936 e935-912.

[38] Bras J, Guerreiro R, Darwent L, Parkkinen L, Ansorge O, Escott-Price V, Hernandez

DG, Nalls MA, Clark LN, Honig LS, Marder K, Van Der Flier WM, Lemstra A,

Scheltens P, Rogaeva E, St George-Hyslop P, Londos E, Zetterberg H, Ortega-

Cubero S, Pastor P, Ferman TJ, Graff-Radford NR, Ross OA, Barber I, Braae A,

Brown K, Morgan K, Maetzler W, Berg D, Troakes C, Al-Sarraj S, Lashley T, Compta

Y, Revesz T, Lees A, Cairns N, Halliday GM, Mann D, Pickering-Brown S, Dickson

DW, Singleton A, Hardy J (2014) Genetic analysis implicates APOE, SNCA and

suggests lysosomal dysfunction in the etiology of dementia with Lewy bodies.

Hum Mol Genet 23, 6139-6146.

[39] Bekris LM, Millard SP, Galloway NM, Vuletic S, Albers JJ, Li G, Galasko DR, DeCarli

C, Farlow MR, Clark CM, Quinn JF, Kaye JA, Schellenberg GD, Tsuang D, Peskind

ER, Yu CE (2008) Multiple SNPs within and surrounding the apolipoprotein E

gene influence cerebrospinal fluid apolipoprotein E protein levels. J Alzheimers

Dis 13, 255-266.

[40] Bekris LM, Galloway NM, Montine TJ, Schellenberg GD, Yu CE (2010) APOE mRNA

and protein expression in postmortem brain are modulated by an extended

haplotype structure. Am J Med Genet B Neuropsychiatr Genet 153B, 409-417.

24

[41] Chang S, ran Ma T, Miranda RD, Balestra ME, Mahley RW, Huang Y (2005) Lipid-

and receptor-binding regions of apolipoprotein E4 fragments act in concert to

cause mitochondrial dysfunction and neurotoxicity. Proc Natl Acad Sci U S A 102,

18694-18699.

[42] Jun G, Vardarajan BN, Buros J, Yu CE, Hawk MV, Dombroski BA, Crane PK, Larson

EB, Alzheimer's Disease Genetics C, Mayeux R, Haines JL, Lunetta KL, Pericak-

Vance MA, Schellenberg GD, Farrer LA (2012) Comprehensive search for

Alzheimer disease susceptibility loci in the APOE region. Arch Neurol 69, 1270-

1279.

[43] Kim S, Swaminathan S, Shen L, Risacher SL, Nho K, Foroud T, Shaw LM,

Trojanowski JQ, Potkin SG, Huentelman MJ, Craig DW, DeChairo BM, Aisen PS,

Petersen RC, Weiner MW, Saykin AJ, Alzheimer's Disease Neuroimaging I (2011)

Genome-wide association study of CSF biomarkers Abeta1-42, t-tau, and p-

tau181p in the ADNI cohort. Neurology 76, 69-79.

25

Tables

Table 1. Demographic characteristics of subjects

DLB/PDD

subjects

Non-demented

PD patients

Statistical

test

P-value

N 156 92 N/A N/A

Age (mean + SD) 76.1 + 6.3 66.5 + 10.3 t=9.2 <0.001

Proportion female

(%)

32.7 41.3 c2=1.9 0.17

Disease duration

in years (mean +

SD)

8.4 + 6.2 9.4 + 6.3 t=1.2 0.21

CSF Aβ42 in ng/L

(mean + SD)

544.7 + 193.6

(n=36)

622.9 + 156.3

(n=79)

t=2.3 0.023

CSF- Aβ42/Tau

(mean + SD)

1.99 + 0.94

(n=36)

2.64 + 0.88

(n=79)

t=3.7 <0.001

26

Table 2. Distribution of TOMM40 poly-T alleles in the non-demented PD patients (n=92)

compared to the PDD/DLB group (n=156). The proportion of subjects within each group

having a specific allele is given in parenthesis. OR was calculated for the indicated allele vs.

all other alleles. P-values were calculated using logistic regression, with PDD/DLB status as

dependent variable and TOMM40 poly-T allele carrier status for each of S/L/VL alleles as

independent variable. P-values<0.017 (0.05/3) were considered statistically significant.

Alleles Dementia status Model 1 Model 2

DLB/PDD,

allele carriers

vs non-

carriers, n

(%)

Non-

demented

PD, allele

carriers vs

non-carriers

n (%)

OR

(95% CI)

P-

value

OR

(95% CI)

P-

value

TOMM40-S 108 (69.2%)

vs 48

(30.8%)

58 (63.0%)

vs 34

(37.0%)

1.75

(0.90-3.39)

0.10 2.36

(1.15-4.82)

0.02

TOMM40-L 75 (48.1%)

vs 81

(51.9%)

26 (28.3%)

vs 66

(71.7%)

2.43

(1.27-4.65)

<0.01 3.89

(0.31-

48.81)

0.29

TOMM40-

VL

84 (53.8%)

vs 72

(46.2%)

57 (62.0%)

vs 35 (38%)

0.44

(0.23-0.84)

0.01 0.44

(0.27-1.06)

0.07

Model 1 = adjustment for age and sex

Model 2= adjustment for age, sex, and APOE4 carrier status

27

Figure 1.

Figure 2.

28

Legend Figure 1

29

Levels of CSF Aβ42 and CSF-TAU byTOMM40 genotype in all subjects (n=115) and

in non-demented Parkinson´s disease (PDND) subjects (n=79) only. The box

represents the interquartile range, with the median indicated in the middle. The error

bars represent the lowest and highest normal values (max 1.5 box lengths from the

lower and upper quartiles, respectively).

After Bonferroni corrections, the following group differences were significant for CSF

Aβ42: S/S vs S/L (p=0.003 for all subjects; p=0.009 for PDND only), S/S vs L/L

(p=0.003 for all subjects; p=0.007 for PDND only), S/S vs L/VL (p=0.104 (NS) for all

subjects, p=0.029 for PDND only), S/L vs S/VL (p=0.001 for all subjects; p=0.012 for

PDND only), S/L vs VL/VL (p<0.001 for all subjects; p<0.001 for PDND only), S/VL vs

L/L (p=0.001 for all subjects; p=0.009 for PDND only), S/VL vs L/VL (p=0.032 for all

subjects; p=0.041 for PDND only), L/L vs VL/VL (p<0.001 for all subjects; p=0.001 for

PDND only), and L/VL vs VL/VL (p=0.001 for all subjects; p=0.001 for PDND only).

The following group differences were significant for CSF Tau: S/S vs S/L (p=0.001),

S/L vs S/VL (p=0.016), and S/L vs VL/VL (p=0.033). None of these group differences

were significant in the PDND group only (all p-values>0.19).

Legend Figure 2

30

Levels of CSF Aβ42 and CSF-TAU by APOE genotype in all subjects (n=115) and in

non-demented Parkinson´s disease (PDND) subjects (n=79) only. The box

represents the interquartile range, with the median indicated in the middle. The error

bars represent the lowest and highest normal values (max 1.5 box lengths from the

lower and upper quartiles, respectively).

After Bonferroni corrections, the following group differences were significant for CSF

Aβ42: e2/e3 vs e2/e4 (p=0.048 for all subjects; p=0.883 (NS) for PDND only), e2/e3 vs

e3/e4 (p=0.013 for all subjects; p=0.076 (NS) for PDND only), e2/e3 vs e4/e4

(p=0.001 for all subjects; p=0.003 for PDND only), e2/e4 vs e3/e3 (p=0.009 for all

subjects; p=0.356 (NS) for PDND only), e3/e3 vs e3/e4 (p<0.001 for all subjects;

p<0.001 for PDND only), e3/e3 vs e4/e4 (p<0.001 for all subjects; p<0.001 for PDND

only).

In all subjects, the following group differences were significant for CSF Tau: e2/e3 vs

e3/e4 (p=0.027) and e3/e3 vs e3/e4 (p=0.001), but none of these differences were

significant in the PDND only (all p-values>0.11)

31

Supplementary material

Legend: Table 3. Associations between TOMM40 poly-T allele carrier status and CSF levels

of Aβ42 and Aβ42/Tau. Linear regression models, adjusted for age and sex, were used,

standardized beta (β) and p-values are given. Data is given for all subjects with available

CSF samples (n=115) and for PDND subjects only (n=79) in parenthesis. Significant values

are marked in bold. P-values<0.017 (0.05/3) were considered statistically significant

Alleles CSF Aβ42 CSF Aβ42/Tau

β (ng/L) p-value β (ng/L / ng/L) p-value

TOMM40-S 0.04 (0.08) 0.70 (0.46) 0.02 (0.11) 0.78 (0.32)

TOMM40-L -0.49 (-0.56) <0.001 (<0.001) -0.49 (-0.49) <0.001 (<0.001)

TOMM40-VL 0.25 (0.09) <0.01 (0.19) 0.20 (0.17) 0.02 (0.12)

32

Legend: Table 4. Associations between TOMM40 poly-T allele carrier status and CSF levels

of Aβ42 and Aβ42/Tau. Linear regression models, adjusted for age sex, and APOE4 carrier

status were used, standardized beta (β) and p-values are given. Data is given for all subjects

with available CSF samples (n=115) and for PDND subjects only (n=79) in parenthesis. P-

values<0.017 (0.05/3) were considered statistically significant

Alleles CSF Aβ42 CSF Aβ42/Tau

β p-value β p-value

TOMM40-S -0.13 (-0.16) 0.10 (0.13) -0.15 (-0.11) 0.04 (0.25)

TOMM40-L -0.13 (-0.38) 0.59 (0.18) 0.02 (-0.13) 0.91 (0.61)

TOMM40-VL 0.15 (0.13) 0.06 (0.18) 0.10 (0.11) 0.17 (0.24)

Legend: Supplementary analyses of TOMM40 poly-T repeat vs dementia status

using tertiles in order to assign TOMM40 poly-T repeat length to categories.

Since 43% of the alleles are 16 in length (and this is the shortest allele length

measured in this dataset), this was set as the cut-off for the S allele in these new

analyses.

S allele: 16 or less

L allele: 17-31

VL allele: 32-39

Associations between allelic variants of TOMM40 poly-T repeat and PDD/DLB status

33

Forty-eight% of the subjects with PDD or DLB were L carriers compared to 29% of

the PDND subjects (P-value=0.011, OR=2.31, 95% CI=1.21-4.39). Fifty-four% of the

PDD/DLB subjects were VL allele carriers compared to 62% of the PDND subjects

(P-value=0.013, OR=0.44, 95% CI=0.23-0.84). Sixty-nine% of the subjects with PDD

or DLB were S carriers compared to 63% of the PDND subjects (P-value=0.098,

OR=1.75, 95% CI=0.90-3.39).

When additionally adjusting for APOE4 allele carrier status, none of these differences

were significant at the level of p<0.017 (data not shown).

Associations between allelic variants of TOMM40 poly-T repeat and CSF levels of

Aβ42 and Tau

In order to test whether the associations between allelic variants of TOMM40 poly-T

repeat and dementia in PD might be mediated via increased AD-related pathology

we also measured CSF levels of Aβ42, and tau in a subpopulation (n=115).

Associations between allelic variants of TOMM40 poly-T repeat and CSF Aβ42 and

Aβ42/Tau were tested using linear regression models in all subjects and in PDND

subjects only, adjusted for age and sex.

L allele carrier status was significantly associated with lower Aβ42 (all subjects: P-

value<0.001, β=-0.48; PDND subjects only: P-value<0.001, β=-0.54), and lower

Aβ42/Tau (all subjects: P-value<0.001, β=-0.46; PDND subjects only: P-value<0.001,

β=-0.44). In all subjects, but not in PDND only, VL allele carrier status was

associated with higher Aβ42 (all subjects: P-value=0.006, β=0.25; PDND subjects

only: P-value=0.090, β=0.19), as well as higher Aβ42/Tau (all subjects: P-

value=0.019, β=0.20; PDND subjects only: P-value=0.120, β=0.17). There were no

34

significant associations between S allele carrier status and CSF Aβ42 or Aβ42/Tau (all

p-values>0.32).

When additionally adjusting for APOE4 allele carrier status these changes were no

longer significant at the level of p<0.017 (data not shown).

35