Question

in Albinism:

- Define albinism in detail

- Name the categories of it

- Draw to compare the metabolic pathway between normal and patient with Albinism

Answer 1

Ans:

• Albinism is a group of inherited congenital disorders characterized in humans by the complete or partial absence of a pigment melanin in the skin, hair and eyes. Albinism results from defective production of melanin from tyrosine through a complex pathway of metabolic reactions. As melanin also plays a role in the development of optic nerves, it is associated with a number of vision defects such as photophobia, nystagmus and amblyopia. Lack of skin pigmentation makes for more susceptibility to sunburn and skin cancers. Most people with albinism have pale skin, eye conditions and are sensitive to the sun. Visual symptoms includes blurred vision, astigmatism and sensitivity to light. Eye defects includes lazy eye, underdeveloped optic nerve and rapid involuntary movement. Skin related symptoms includes loss of colour and skin burn. No cure exists, but skin can be protected and eye conditions can be treated.

• Categorization of albinism: Different gene defects categorize the numerous types of albinism. It mainly includes:

(i) Oculocutaneous Albinism (OCA): There are four subtypes of OCA named OCA1 (defects in tyrosinase enzyme), OCA2 (defect in OCA2 gene), OCA3 (defect in TYRP1 gene) and OCA4 (defect in SLC45A2 proein).

(ii) Ocular Albinism: It is the result of gene mutation on X chromosome.

(iii) Hermansky-Pudlak Syndrome: Rare form of albinism due to defect in one of the eight genes.

(iv) Chediak-Higashi Syndrome: Rare form of albinism due to defect in LYST gene.

(v) Griscelli Syndrome: It is an extremely rare genetic disorder due to defect in one of the three genes.

   

• Metabolic pathway between normal and patient with albinism: Albinism results from defective production of melanin from tyrosine through metabolic reactions.

Normal	Dietary Protein Tyrosine DOPA Dopaquinone Normal melanin production
Albinism Patient	Dietary Protein Tyrosine DOPA Reduced or No melanin production