Publish date: Posted on
Last updated: May 11, 2022
Keywords #
albinism
oculocutaneous albinism
albino
OCA
OCA1
OCA2
OCA3
OCA4
Diagnosis #
Oculocutaneous albinism (OCA) is a group of autosomal recessive genetically inherited disorders with impaired melanin biosynthesis leading to reduced to absent pigmentation of the skin, hair and eyes. There are four main subtypes of OCA with varying degrees of melanin production and disease severity. OCA1a is the most severe subtype with no melanin production throughout life. OCA2, OCA3 and OCA4 show varying degrees of pigment accumulation throughout life and varying degrees of visual acuity. Skin manifestations of the disease include hypopigmented skin, hair and nails relative to family members and members of the same ethnic group.[1] Reduced or absent melanin in the skin leads to photosensitivity and increased skin cancer risk. People with OCA have increased risk of early onset skin-cancer presenting as early as adolescence. Squamous cell carcinoma is the most common type of skin cancer in patients with OCA.[2] Ocular manifestations of the disease include reduced visual acuity, strabismus, nystagmus, and photosensitivity.[1] Albinism also manifests as social discrimination due to appearing different that others, this being more prominent in some parts of the world.[3] People with albinism have no difference in lifespan, development, intelligence or fertility from the general population.[1]
Key Concepts #
- Albinism is caused by gene mutations associated with the melanin biosynthesis pathway leading to decreased or absent melanin production.
- There is a wide range of disease severity and presentation classified into 4 main subtypes based on which gene is mutated (OCA1, OCA2, OCA3, OCA4).
- OCA1 is the most severe subtype and is characterized by no melanin production throughout life.
- OCA2, OCA3 and OCA4 have varying degrees of pigment accumulation and visual acuity throughout life.
- People with albinism are at increased risk of early onset skin cancer with squamous cell carcinoma being the most common.[2]
- People with albinism have no difference in lifespan, development, intelligence or fertility from the general population.[1]
- No treatment is available for albinism but management of the condition includes strict sun protection and early and frequent skin and ophthalmologic exams.[1]
Epidemiology #
Albinism affects 1 in 17,000 to 1 in 20,000 people worldwide with 1 in 70 people estimated to carry one of the albinism alleles. OCA2 is the most common subtype of albinism in the world with the highest prevalence being in Africa. OCA1 and OCA2 are the most common types of albinism in the United States. The prevalence of albinism in the United States is estimated at 1 in 37,000.[4]
Clinical Features #
Cutaneous manifestations:
- Hypopigmented skin relative to family members and members of the same ethnic group
- Hypopigmented hair relative to family members and members of the same ethnic group ranging from white, blonde, reddish-blonde, red, reddish-brown, yellowish-red to brown.
Ocular manifestations:
- Reduced eye pigmentation ranging from pink blue, green, gray to light brown
- Iris transillumination on slit lamp exam
- Foveal hypoplasia
- Strabismus
- Nystagmus
- High refractive errors including hyperopia, myopia and astigmatism
- Absent or reduced fine depth perception
Differential Diagnoses #
- Chediak Higashi Syndrome
- Hermansky-Pudlak syndrome
- Griscelli Syndrome
- Waardenburg Syndrome type II
- Ocular albinism
- Vici Syndrome
- Angelman Syndrome
- Prader-Willi Syndrome
- Tietz albinism-deafness syndrome
Diagnostic Workup #
Oculocutaneous albinism is a clinical diagnosis based on hypopigmented skin, hair, nails and irises and characteristic ocular findings including photophobia, nystagmus, iris transillumination, foveal hypoplasia and reduced visual acuity. Subtypes OCA2, OCA3 and OCA4 are difficult to differentiate clinically thus molecular testing using either a gene panel or genomic sequencing can be done to establish a diagnosis for genetic counseling. If associated systemic symptoms are present in addition to oculocutaneous findings, further work up for Chediak Higashi or Hermansky-Pudlak syndrome is warranted.[1]
Treatment #
There is no definitive treatment for albinism. Management of albinism includes strict lifelong sun protection. Due to the increased risk of skin cancer, patients are advised to have total body skin examinations every 6-12 months starting in adolescence.[5] Patients should receive ophthalmologic examination by age four to six months of age with frequent re-examination thereafter.[6] Ophthalmologic management includes glasses or contact lenses for high refractive errors, filtering lenses for photophobia, and corrective eye patches or surgery for strabismus.[7]
References #
- Grønskov, Karen et al. “Oculocutaneous albinism.” Orphanet journal of rare diseases 2 43. 2 Nov. 2007, doi:10.1186/1750-1172-2-43
- Kiprono, Samson Kimaiyo et al. “Histological review of skin cancers in African Albinos: a 10-year retrospective review.” BMC cancer 14 157. 6 Mar. 2014, doi:10.1186/1471-2407-14-157
- Cruz-Inigo, Andres E et al. “Albinism in Africa: stigma, slaughter and awareness campaigns.” Dermatologic clinics 29,1 (2011): 79-87. doi:10.1016/j.det.2010.08.015
- Marçon, Carolina Reato, and Marcus Maia. “Albinism: epidemiology, genetics, cutaneous characterization, psychosocial factors.” Anais brasileiros de dermatologia 94,5 (2019): 503-520. doi:10.1016/j.abd.2019.09.023
- Fogel, Alexander L et al. “Genetic diseases associated with an increased risk of skin cancer development in childhood.” Current opinion in pediatrics 29,4 (2017): 426-433. doi:10.1097/MOP.0000000000000514
- Anderson, Jill et al. “Efficacy of spectacles in persons with albinism.” Journal of AAPOS : the official publication of the American Association for Pediatric Ophthalmology and Strabismus 8,6 (2004): 515-20. doi:10.1016/j.jaapos.2004.08.008
- Villegas, Victor M et al. “Visual acuity and nystagmus following strabismus surgery in patients with oculocutaneous albinism.” Puerto Rico health sciences journal 29,4 (2010): 391-3.
