Inheriting altered copies of at least 12 different genes that do not work properly is the cause of most types of albinism. About 20% of individuals with albinism remain molecularly unresolved in all genetic diagnosis centers due to the mutation status in known genes. Hypopigmentation, white blood cell abnormalities, short lifespan, eye diseases, and skin diseases are seen. It is an inherited disease that can be transmitted both as an autosomal recessive inheritance and X-linked, depending on the type. There are 2 types of albinism:
- Oculocutaneous albinism (OCA)
- Ocular albinism (OA)
OCA is the most common and only autosomal recessive type. It affects the skin, hair, and eyes. OA, on the other hand, is the rarer type and in addition to autosomal recessive transmission, some types can also be X-linked. Mainly affects the eyes1,2,3.
Gene | Chromosomal locationa | Albinism typeb | OMIMc | ORPHANETd | HGNCe |
TYR | 11q14.3 | OCA1f | #203100 | ORPHA352731 | HGNC:12442 |
OCA2 | 15q12-q13.1 | OCA2 | #203200 | ORPHA79432 | HGNC:8101 |
TYRP1 | 9p23 | OCA3 | #203290 | ORPHA79433 | HGNC:12450 |
SLC45A2 | 5p13.2 | OCA4 | #696574 | ORPHA79435 | HGNC:16472 |
n.d. | 4q24 | OCA5 | #615312 | n.d. | HGNC:44139 |
SLC24A5 | 15q21.1 | OCA6 | #609802 | n.d. | HGNC:20611 |
C10orf11 | 10q22.2-q22.3 | OCA7 | #615179 | ORPHA352745 | HGNC:23405 |
GPR143 | Xp22.2 | OA1 | #300500 | ORPHA54 | HGNC:20145 |
LYST | 1q42.3 | CHS1 | #214500 | ORPHA167 | HGNC:1968 |
HPS1 | 10q24.2 | HPS1 | #203300 | ORPHA231500 | HGNC:5163 |
AP3B1 | 5q14.1 | HPS2 | #608233 | ORPHA183678 | HGNC:566 |
HPS3 | 3q24 | HPS3 | #614072 | ORPHA231512 | HGNC:15597 |
HPS4 | 22q12.1 | HPS4 | #614073 | ORPHA231500 | HGNC:15844 |
HPS5 | 11p15.1 | HPS5 | #614074 | ORPHA231512 | HGNC:17022 |
HPS6 | 10q24.32 | HPS6 | #614075 | ORPHA231512 | HGNC:18817 |
DTNBP1 | 6p22.3 | HPS7 | #614076 | ORPHA231531 | HGNC:17328 |
BLOC1S3 | 19q13.32 | HPS8 | #614077 | ORPHA231537 | HGNC:20914 |
BLOC1S6 | 15q21.1 | HPS9 | #614171 | ORPHA280663 | HGNC:8549 |
Table: Human genes related to albinism. OCA2 is the most common form worldwide4.
In addition to having different causes, they can also have different symptoms. In Hermansky-Pudlak syndrome, there are symptoms similar to OCA, but intestinal, heart, kidney, and lung diseases or hemophilia are more likely, while in Chediak-Higashi syndrome, a person’s hair may appear silvery and their skin may appear slightly gray. Infection is more likely as there may be defects in the white blood cells. The reasons for the different types are also different. For example, with a mutation in the OCA1 tyrosinase gene; OCA2 with a mutation in the OCA2 gene; by mutation of OCA3 tyrosinase-associated protein; OCA4 is caused by mutations in the membrane-associated carrier protein gene8,9,10.

About one in 17,000 people suffer from albinism. They have hypersensitivity to the sun, susceptibility to skin cancer, and retinal abnormalities. Possible eye problems linked to albinism include:
Some retinal abnormalities may occur due to little or no melanin. The reason is that melanin plays an important role in the development of the retina. Possible eye problems of people with albinism are poor vision, astigmatism, photophobia, nystagmus, and strabismus4,5.
Diagnosis
The remarkable features of these patients, whose symptoms can be seen in all races and ages, are that their hair, eyelashes, and skin are white. The irises are light blue-pink, but completely translucent. In addition to being a visible disease, electrodiagnostic tests are also used to diagnose albinism. In these tests, electrodes are attached to the skin to check the connection between the eye and the part of the brain that controls vision3,6,7.

Conclusion
People with albinism have different symptoms and severity depending on the mutation location. There is no cure, but it is very important for the person needs to protect himself, especially against the sun. In addition, they lead their lives like other people and there is no condition that affects their intelligence3.
References:
- Increasing the complexity: new genes and new types of albinism https://onlinelibrary.wiley.com/doi/10.1111/pcmr.12167# 09.12.2022 / 16.30
- Albinism https://www.sciencedirect.com/science/article/pii/B9780123735539000067 09.12.2022 / 17.00
- Albinism https://www.nhs.uk/conditions/albinism/ 09.12.2022 / 17.30
- Oculocutaneous albinism Grønskov, K., Ek, J. & Brondum-Nielsen, K. Okülokutanöz albinizm. Orphanet J Rare Dis 2 , 43 (2007). 10.12.2022 / 20.15
- Oculocutaneous albinism Wei, A.H., Zang, D.J., Zhang, Z. et al. (2013b). Exome sequencing identifies SLC24A5 as a candidate gene for nonsyndromic oculocutaneous albinism. J. Invest. Dermatol. 133, 1834–1840. 10.12.2022 / 21.55
- Oculocutaneous albinism Witkop CJ: Albinizm: hematolojik depo hastalığı, cilt kanserine duyarlılık ve her türlü okülokütanöz ve oküler albinizmde paylaşılan optik nöronal defektler. Ala J Med Sci. 1979, 16: 327-330. 10.12.2022 / 21.20
- Albinism Kral RA, Summers CG: Albinizm. Dermatol Clin. 1988, 6: 217-228. 11.12.2022 / 12.40
- Oculocutaneous albinism Newton JM, Cohen-Barak O, Hagiwara N, Gardner JM, Davisson MT, King RA, Brilliant MH: Mutations in the human orthologue of the mouse underwhite gene (uw) underlie a new form of oculocutaneous albinism, OCA4. Am J Hum Genet. 2001, 69: 981-988. 10.1086/324340. 11.12.2022 / 13.20
- Mutation for albinism Boissy RE, Zhao H, Oetting WS, Austin LM, Wildenberg SC, Boissy YL, Zhao Y, Sturm RA, Hearing VJ, King RA, Nordlund JJ: Mutation in and lack of expression of tyrosinase-related protein-1 (TRP-1) in melanocytes from an individual with brown oculocutaneous albinism: a new subtype of albinism classified as “OCA3”. Am J Hum Genet. 1996, 58: 1145-1156. 11.12.2022 / 13.45
- Different types of albinism Rinchik EM, Bultman SJ, Horsthemke B, Lee ST, Strunk KM, Spritz RA, Avidano KM, Jong MT, Nicholls RD: A gene for the mouse pink-eyed dilution locus and for human type II oculocutaneous albinism. Nature. 1993, 361: 72-76. 10.1038/361072a0. 11.12.2022 / 14.00
Figure References:
- https://onlinelibrary.wiley.com/doi/10.1111/pcmr.12167# 11.12.2022 / 14.30
- https://ojrd.biomedcentral.com/articles/10.1186/1750-1172-2-43#Tab1 11.12.2022 / 13.40
Inspector: Nadir KERESTECİ