ALBINISM presentation and their effect in the eye

albinism

1. ALBINISM Melanogenesis is the process of melanin synthesis. Takes place in melanocytes located in the basal layer of the epidermis Melanocytes transfer melanosomes to keratinocytes via their dendrites Sites – skin, hair, eyes, inner ear

2. All humans regardless of skin colour, have approx. the same number of epidermal melanocytes at a particular anatomic site Ethnic variation in skin colour results from differences in melanosome properties (size) and not from numbers

3. ALBINISM A hypopigmentary disorder characterised by a partial or total lack of melanin pigment in the eyes, skin and hair It is a result of inheritance of recessive genes such that body does not produce the usual amount of melanin Most humans and animals with albinism appear white or pale

4. Autosomal recessive disorder

5. Classification Ocular albinism Only the eyes lack pigment Skin and hair colour are normal Oculocutaneous albinism Pigment is lacking in skin, hair and eyes

6. Sub types Ocular albinism type I (OAI) Is the most common variety of ocular albinism. Caused by a mutation in a gene on the X-chromosome hence a disorder of males Usually associated with nystagmus

7. Ocular albinism type 2 (OA 2 ) Mostly affects males, but females can be affected also. Females are carriers Frequently linked with colour blindness and nyctalopia Ocular albinism 3 (OA 3) A non X-linked variant common in the Amish populations

8. Ocular findings Various degrees of congenital nystagmus Hypopigmentation of iris leading to iris translucency Reduced pigmentation of the retinal pigment epithelium

9. Ocular findings Reduced visual acuity due to foveal hypoplasia and misrouting of optic fibres Refractive errors sometimes a degree of color vision impairment Photophobia may be prominent

10. Oculocutaneous albinism Has sub types of OCA1A , 1B, OCA 2, OCA 3 and OCA4, caused by mutations in different genes OCA 1A is the most severe type characterized by a complete lack of melanin production throughout life. OCA1B, OCA2, OCA3 and OCA4 are milder and show some pigment accumulation over time.

11. OCA 1 Prevalence of approximately 1 per 40,000 least amount of melanin Pts usually have very pale skin with white or yellow hair and light blue eyes Caused by an alteration of the tyrosinase gene Two variations: OCA Ia OCA Ib

12. OCA Ia There is no pigment production The hair is usually white and skin very pale Vision ranges from 20/200 to 20/400 OCA Ib The patients can tan and develop hair pigment Several subtypes reported

13. OCA 1

14. Oculocutaneous albinism type 2 Most common type of albinism Caused by mutation of the P gene (OCA2 protein) Patients have more pigment and better vision than those with type 1 albinism Pigment can develop into freckles or moles Affected patients have yellow hair, pale skin and hazel, grey or blue eyes

15. OCA 2

16. Oculocutaneous albinism type 3 Also called Rufous oculocutaneous albinism Reported to affect 1:8,500 individuals in Africa, but very rare in Caucasians and Asiatic populations Caused by mutation of the tyrosinase -related protein-1(Tyrp-1) gene

17. Characteristics of OCA 3 Reduced pigmentation in the skin, eyes and hair Reddish-brown skin Ginger hair, Red hair, Hazel / Brown iris Eye problems are milder than the other types

18. Oculocutaneous albinism type 4 Very rarely seen outside Japan Accounts for 24% of cases of albinism Can only be distinguished from type 2 through genetic testing Caused by mutation of membrane-associated transporter protein (MATP) gene

19. Common complains associated with albinism Sun burns Solar cheilitis Solar elastosis Solar keratosis Skin carcinomas Photophobia Poor vision Stigma and discrimination

20. Sunburns

21. Solar keratosis

22. Solar cheilitis

23. Solar elastosis

24. Don’t ignore!

25. Skin cancers

26. Management Albinism can not be cured! Some measures put in place to improve the quality of life Improve vision Protect eyes from sunlight by use of sun glasses Large print material/ reading glasses/ magnifiers Use of front seats especially in class

27. Sun protection Long-sleeved heavy shirts Trousers/ long dresses/skirts Wide-brimmed hats Sunscreen lotion and lip balms

28. Prevention Early diagnosis and ‘treatment’ Health education Sun protection Counselling , counselling and counselling

29. Wide brimmed hat

30. Recommended hat with tail

31. Modified school uniforms