Albinism is a congenital disorder characterized by partial or complete lack of melanin pigment in the skin, hair, and eyes. It results from inherited recessive gene alleles and affects the production of melanin through defects in enzymes involved in melanin synthesis. There are two main types of albinism in humans - oculocutaneous albinism (OCA), which affects pigment in the eyes, skin, and hair; and ocular albinism (OA), which only affects pigment in the eyes. OCA can be further classified into 4 types based on the genetic defects involved. Vision problems commonly associated with albinism include nystagmus, strabismus, photophobia, refractive errors, and

2. What isAlbinism?Albinism(from Latin albus ‘’white’’) is a congenital disorder characterised by the partial or complete absence of the pigment in the skin,hair,eyes due to absence or defect of an enzyme involved in the production of melanin(pigment) .Albinism results from inheritance of recesssive gene alleles. Albinism is known to affect all vertebrates(including humans).Albino patients

3. Albinism classification in humansThere are two main categories of albinism in humans:-Oculocutaneous albinism (OCA)– This type of albinism is characterised by lack of pigments in eyes,skin,hair .It is of 4 types-OCA1(OCA1A,OCA1B), OCA2. OCA3,OCA4.Ocular albinism(0A)- People having ocular albinism only lacks pigment in the eyes.They usually have normal skin and hair color,although its typically lighhter than either parent.

4. Oculocutaneous albinism type1(OCA1)- It is tyrosinase – related albinism results from a genetic defect in an enzyme called tyrosinase. This enzyme helps the body to change amino acid tyrosine into the pigment. There are two subtypes of OCA1(OCA1A and OCA1B).OCA1A- In OCA1A,The enzyme is inactive and no melanin is produced,leading to white hair and very light skin.OCA1B-In OCA1B,The enzyme is minimally active and a small amount of melanin is produced,leading to hair that may darken to blonde,yellow/orange or even light brown,as well as slightly more pigment in the skin.Oculocutaneous albinism type2(OCA2)-It is a P-gene albinism results from a genetic defect in the p-protein that helps the tyrosinase enzyme to function.Individuals with OCA2make a minimal amount of melanin pigment and can have hair color ranging from very light blonde to brown.

5. Oculocutaneous albinism type3(OCA3)-It is rarely described and results from a genetic defect in TYRP1, a protein related to tyrosinase. Individuals with OCA3 can have substantial pigment.Oculocutaneous albinism type4(OCA4)-It results from a genetic defect in the SLC45A2 protein that helps the tyrosinase enzyme to function.Individuals with OCA4 make a minimal amount of melanin pigment similar to persons withOCA2.

7. Ocular albinism(OA1)-It is caused by a change in the GPR143 gene that plays a signalling role that is especially important to pigmentation in the eye. OA1 follows a simpler pattern of inheritance because the gene for OA1 is on X chromosome. Female has 2 copies of X chromosomes while males have only one copy(another Y). To have Ocular albinism, a male only need to inherit one changed copy of the gene for ocular albinism from his carrier mother. Therefore almost all the people with OA1 are males.NOTE- If female child is said to have ocular albinism, their parents should be suspicious.while possible if the mother is a carrier of ocular albinism and father has ocular albinism,it is extremely rare case.

8. CVS(chorionic villous sampling)-cells in the fluid is examined to see if they have an albinism gene from each parent.

9. Vision rehabilitationEye problems in albinism result from abnormal development of the eye because of lack of pigment and often include: Nystagmus- Regular horizontal back and forth movement of the eyes.Strabismus- Muscle imbalance of the eyes “crossed eyes”(esotreopia) “lazy eye” or an eye that deviates out(exotropia).Photophobia- Sensitivity to bright light and glare.Refractive error- People with albinism may be either farsighted or near sighted and usually have astigmatism.Fovea hypoplasia- The retina , the surface inside the eye that receives light,does not develop normally before birth and in infancy.Optic nerve misrouting- The nerve signals from the retina to the brain does not follow the usual nerve routes.In albinistic patients, light can pass through the iris as well due to lack of pigment.

10. Visual modificationsThe human eye normally produces enough pigment to color the iris and lend opacity to the eye.however, there are cases in which eyes of an albinistic patients appear red or purple depending upon the amount of pigment present. This visual problems associated with albinism arise from a poorly developed Retinal Pigment Epithelium(RPE) due to lack of melanin.

11. Albino’s have poorly developed (RPE)

12. Skin modificationsMost albinistic humans appear white or very pale as the melanin pigments responsible for brown,black colorations are not present.Because they lack the dark pigment melanin, which helps protect the skin burn more easily from overexposure.The albinistic are generally healthy as the rest of the population with growth and development occurring as normal, and albinism by itself does not cause mortality, although the lack of pigment increases the risk of skin cancer and other related problems.