Albinism

Albinism is a genetic condition where people are born without the usual pigment (color) in their bodies. Their bodies aren't able to make a normal amount of melanin, the chemical that is responsible for eye, skin, and hair color. So most people with albinism have very pale skin, hair, and eyes.

1. ALBINISM Dr. V. MAGENDIRA MANI., M.Sc., M.Phil., Ph.D.,TNSET Assistant Professor of Biochemistry Islamiah College (Autonomous), Vaniyambadi [email protected] ; 9486000227

2. Overview Albinism "white“ also called Hypo‐pigmentation, achromia, achromasia, or achromatosis) It is a congenital disorder characterized by the complete or partial absence of pigment in the skin, hair and eyes. Albinism is caused by mutation or an alteration of the gene that makes the melanin pigment

3. It is due to absence or defect of tyrosinase, a copper-containing enzyme involved in the production of melanin. Albinism results from inheritance of recessive gene alleles and is known to affect all vertebrates, including humans. ALBINO : organism with complete absence of melanin ALBINOID or ALBINIC : an organism with only a diminished amount of melanin.

4. Melanin • is a pigment or a substance that gives the skin and hair its natural color. • It also gives color to the iris of the eye, feathers, and scales. • It is synthesized from the amino acid tyrosine. • In the skin, melanin is formed by cells called melanocytes.

5. There are three basic types of melanin Eumelanin: have black and brown color. Pheomelanin: have red or yellow color, responsible for red hair and freckles. Neuromelanin: is found in the brain, though its function remains obscure

6. Melanin provides a natural protection against the harmful effects of ultraviolet rays of the sun. 2. It is also absorb heat from the sun. 3. It is important for sharpness of vision.

7. TYPES OF ALBINISM two main categories of albinism Ocular albinism 2. Oculocutaneous

8. Affecting the eyes only eyes lack melanin pigment skin and hair appear normal or only slightly lighter accounts for 10 to 15 percent of all albinism cases Eye color may be in the normal range but there is no pigment in the retina Ocular albinism

9. 2. Oculocutaneous most common form of albinism Affecting the eyes, skin and hair. People with this type of albinism have white or pink hair, skin, and iris color , as well as vision problems 4 main subtypes OCA1 OCA2 OCA3 OCA4

10. OCA1 white hair very pale skin light-colored irises

11. OCA2 minimal amount of melanin pigment less severe skin creamy white color hair may be light yellow, blond, or light brown

12. OCA3 usually affects dark-skinned people reddish-brown skin ginger or red hair hazel or brown irises

13. OCA4 similar symptoms to OCA2 light skin yellow, blond or light brown hair occurs frequently in the Japanese and Korean populations

14. Interestingly, individuals with phenylketonuria can have light skin and hair at birth because of low levels of tyrosine. However, phenylketonuria are not albinos, because they obtain sufficient amounts of tyrosine in their diets to support melanin biosynthesis.

15. Characteristics Little to no melanin (important pigment) in eyes, skin, and hair Two main problems- Skin Problems & Eye Problems Skin Problems They have very fair skin which is prone to burn easily in the sun (sunburn). at higher than average risk of skin cancer no natural protection against the sun

16. Eye Problems Eyes are usually blue or light brown, but can sometimes appear red or grey eyes and vision is impaired Photophobia - sensitivity to light Nystagmus - involuntary, rhythmic eye movements Squint - where the eyes point in different directions Strabismus: muscle imbalance of the eyes - crossed eyes

17. Esotropia -lazy eye, exotropia -eye that deviates out Foveal hypoplasia -retina does not develop normally before birth and in infancy Astigmatism, irregular shaped cornea Optic nerve misrouting: the nerve signals from the retina to the brain do not follow the usual nerve routes Amblyopia, decrease in acuity of one or both eyes due to poor transmission to the brain

18. Race Albinism affects all persons of races. Parents of most children with albinism have normal eye color for their ethnic background. Sex Both males and females can be affected. However, in OA 1 (X-linked recessive OA), males are affected, while females are only carriers. Age All types of albinism are usually congenital

19. The morbidity associated with albinism pertains to visual impairment, skin photosensitivity, and increased cutaneous cancer risk. Patients who have syndromes associated with albinism may have hearing difficulties or abnormalities of blood clotting. Albinism also has social ramifications because patients may feel alienated as a result of the difference in appearance from their families, peers, and other members of their ethnic group. Mortality/Morbidity

20. Prevalence An estimated 1 in 17,000 people have one of the types of Albinism Oculocutaneous Albinism (OCA) happen by 1 per 40,000 of the population Ocular Albinism (OA) happen by 1 per 15,000 of the population.

21. Happens all over the world. • Affects all vertebrates. • Affects people from all races. • Effects men and women of all ages. • Albinism has been observed in many animals also. Albinism is not associated with mortality

22. Genetics of Albinism Most types of albinism are inherited as an Autosomal recessive but some types are X linked Recessive Autosomal Recessive: • Most types of albinism are inherited when an individual receives the albinism gene from both parents. • If parents are carriers, the child has a 25% chance of being completely normal, a 50% chance of being a carrier, and a 25% chance of getting albinism.

23. X‐linked Recessive The exception: some types of ocular albinism, which is passed from mothers to their sons

24. Prognosis Growth, development and intellectual development in the albino child are normal. • Vision is invariably severely impaired. • Albinism does not affect the expected lifespan. • People with albinism may be limited in their activities because they can't tolerate the sun.

25. Albinism (rregular pigmentation) can first appear at birth detected. Diagnosis is based on the examination of the skin, hair and eyes. The most accurate way to determine albinism is genetic test, for example : Chorionic Villus Sampling Test (CVS) and Amniocentesis can identify albinism during the second trimester of pregnancy. Diagnosis

26. Hair from the scalp can be used to assess tyrosinase activity by determination the DOPA and melanin concentration. DOPA and melanin assessed by a radioactive biochemical assay, in which the samples are incubated with a radiolabelled tyrosine precursor and the amount of radiolabel released after enzymatic conversion quantified spectrophotometrically.

27. TREATMENT no cure for albinism Treatments only reduce the symptoms For Skin wear protective clothing, hats Always wear special UV protective clothing to reduce sunburn risk Children should receive annual skin assessments to screen for skin cancer or lesions that could lead to cancer

28. For Eyes Wear Glasses or lenses . Wear dark Sunglasses (UV protected) may relieve photophobia. Eye muscle surgery is sometimes recommended to correct abnormal eye movements (Nystagmus). Children should receive annual examinations by an Ophthalmologist

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