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The effect of an extra X or Y chromosome on language

development

Dorothy V. M. Bishop

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Human chromosomes

One of each pair inherited from mother, one from father

X and Y are sexchromosomes:usually XX in girlsand XY in boys

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Extra X or Y chromosome

• 47, XXX (trisomy X, triple X syndrome)– affects 1 per 1000 girls

• XXY – Klinefelter’s syndrome– affects 1 per 650 boys

• XYY– affects 1 per 1000 boys

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How is extra X or Y chromosome detected?

• Requires a blood test

• Often it is NOT detected because children look normal and don’t have major problems

• May be picked up on prenatal screening

• May be picked up if child is tested because of educational difficulties

• XXY can be detected because child doesn’t experience normal changes of puberty; or may be identified in adulthood during investigations for infertility

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What features are associated with having an extra X or Y chromosome? (1)

N.B. Huge variation from child to child: no one feature is found in all. Some affected children have NO problems

•Features documented in research studies for all three trisomies:– Children tend to be taller than usual

– Speech and language difficulties are common

– Mild autistic features (more severe autism in a minority)

– Poor muscle tone

– Social anxiety: esp. in XXX and XXY – extremely shy and worried about talking in public

– Social immaturity: prefers company of younger children; may be ‘easily led’ by older children

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What features are associated with having an extra X or Y chromosome? (2)

• Features noted in parent reports, but not much hard data and unclear how common:– Dental problems– ‘Growing pains’ in arms and legs– Hypersensitivity to touch - makes choice of clothes an issue– “Meltdowns” – sudden explosions of rage which go as quickly as

they come

Specific to Klinefelter syndrome (XXY)– Failure to go through puberty; infertility in adulthood

N.B. Puberty/fertility usually normal in XXX and XYY

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Research on sex chromosome trisomies

• 1960s: Newborn screening studies done to look at unbiased samples

• Most children attend mainstream school

• But increased educational difficulties, especially affecting language, in all three trisomies, though with some differences in cognitive profile.

Leggett, V., Jacobs, P., Nation, K., Scerif, G., & Bishop, D. V. M. (2010). Neurocognitive outcomes of individuals with a sex chromosome trisomy: XXX, XYY, or XXY: a systematic review. Developmental Medicine and Child Neurology, 52(2), 119-129. doi: 10.1111/j.1469-8749.2009.03545.x

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Recent study based on parental interviews and questionnaires

Bishop, D. V. M., et al (2011). Autism, language and communication in children with sex chromosome trisomies. Archives of Disease in Childhood, 96, 954-959. doi: doi:10.1136/adc.2009.179747

Children identified on prenatal screening or in first year of life

•30 with XXX•19 with XXY•21 with XYY

Compared with brothers and sisters in same age range (4 to 15 yr)

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Rates of reported educational problems

Substantial individualvariation

XXX XXY XYYSpecial educational needs

14% 32% 48%

Speech and language therapy

24% 47% 71%

Autism spectrum disorder diagnosis

0% 11% 20%

Rates of SEN and SALT generally higher than in general population or in brothers and sisters. ASD rate in boys contrasts with around 1.6% in general population

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Is sex chromosome trisomy a common cause of language impairment/autism?

NO!•Konstantareas & Homatidis (1999)

– series of 127 children diagnosed with autism• One case of XXY (and 7 with other chromosome anomalies)

•Robinson (1991)– 65 boys and 17 girls with SLI

• Three cases of XXY

These rates are higher than in the general population, but the majority of children with language impairment or autism have the usual number of chromosomes, 46.

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More information on the web

N.B. Quality of information on the web is very variable, and some of it highly inaccurate.

These are reliable sources:

Unique: http://www.rarechromo.co.uk/html/home.aspfor information on trisomy X and XYY

Klinefelter’s syndrome association UK: http://www.ksa-uk.net/

KS&A (USA) http://www.genetic.org/

For further readingsee reference list on:

http://www.slideshare.net/RALLICampaign/an-extra-x-or-y-chromosome