Welcome

Albinism: the basics

Mr Jay Self BM FRCOphth PhD Associate Professor and Consultant Ophthalmologist Miss Helena Lee Specialty registrar and Clinical Lecturer

What we think we know (and what we are starting to realise….)

3

Melanin Biosynthesis

4

Types of Albinism

Oculo-cutaneous Albinism

(OCA)

Ocular Albinism

(OA)

Albinism

5

Eye features in albinism

6

Oculo-cutaneous albinism (OCA)

• Syndromic

– Chediak-Higashi, Hermansky-Pudlak etc.

• Non-syndromic

– OCA1 (TYR gene) : OCA1a (severe) and OCA1b (less severe)

– OCA2 (OCA2 gene) : (less severe)

– OCA3 (TYRP1 gene) : (rufous albinism)

– OCA4 (SLC45A2 gene) : (less severe)

– OCA5-7 : less data and variable features

• ‘Other associations’ – ie Prader-Willi/Angelman Syndrome and OCA2

7

Oculo-cutaneous albinism (OCA)

• Siblings of an affected child have ¼ chance of albinism

• Children of someone with albinism are unlikely to have albinism (?1/400)

• Same rules for boys and girls

8

Ocular albinism (OA)

• X-linked (GRP143 gene)

• Some subtle features in females

• Eye signs only

9

Ocular albinism (OA)

• Affected Dad’s can’t pass to sons but all daughters will be carriers

• Affected Mum’s will pass to 50% all kids but girls will be carriers and boys will have the condition

However…..........

11

12

What’s happening here?

NAD OCT

No Nystagmus Nystagmus No Nystagmus No Nystagmus Nystagmus

NAD TED

OCT ??

NAD TED

NAD VEP NAD VEP Abnormal VEP NAD VEP Abnormal VEP

Probands

Parents and siblings

• 50% have clinical

signs of

underlying

diagnosis

• Parent/sib exam

informative in

20%

14

What we are starting to realise

• Ocular features of albinism are COMMONLY incomplete

• No ocular feature is pathognomic (foveal hypoplasia is the closest)

• Ocular features are differentially sensitive to melanin

• Genetic background and common variants are important

Albinism Partial Albinism

17

What we would like to know

• How damage to the melanin pathway causes the eye features?

• What functions these proteins have in the developing retina?

• Are some features ‘caused’ by the others?

• What is the incidence of pigmentary gene related eye disease?

• How complex is the pigmentary background in affecting the features?

• Are people with albinism ‘protected’ from some retinal conditions?

18

Why we want to know

• We may be able to intervene to reduce the visual loss associated with pigmentary disorders with:

– Gene modification

– Replacing enzymes in the pathway

– Driving the pathway through other means

19

How can we help at the moment?

What can Mum’s and dad’s do?

• Push for thorough examination

• Ask to see an expert

• Ask for genetics

• Make sure the basics are done

• Get involved in research

• Any child with reduced vision and a family hx should have be investigated for subtle albinism

MOST IMPORTANT MESSAGE

• Remember: Children with albinism can live normal lives with just a few extra things to think about. They will live with albinism and don’t have to let it define who they are.

Thanks for listening

•Any questions?