“Albinism”: in fact a symptom part of Albinism and of a number of syndromes

• Albinism is a rare genetic condition affecting around 1 out of 17000 individuals (can vary geographically).
• Albinism is characterized by severe and handicapping deficits in the visual system in association with a most variable hypopigmentation phenotype: visual defects include: foveal hypoplasia, reduced pigmentation of retinal pigment epithelium cells, misrouting of the optic nerves at the chiasm, reduced pigmentation in the iris, photophobia and nystagmus.
• Hypopigmentation may affect the eyes, skin and hair (oculocutaneous albinism, OCA), or be limited to the eyes (ocular albinism, OA).

• Also, there are several syndromic forms of albinism (e.g., Hermansky-Pudlak and Chediak-Higashi syndromes) in which the described hypopigmented and visual phenotypes coexist with more severe pathological alterations.

Genetics

• To date, mutations in up to 18 genes have been associated with different types of albinism.
• Recently:
  • a new locus has been found to be associated with OCA (called OCA5): it has been mapped to the 4q24 human chromosomal region (but the gene itself has not been identified yet).
  • OCA6 and OCA7 occur when new genes are mutated SLC24A5 and C10orf11 respectively.

Contributors

Dr Christophe Hsu – dermatologist. Geneva, Switzerland

Source of information: 2014 (09) – Increasing the Complexity: New Genes and New Types of Albinism. Lluis Montoliu, Mónica Martínez-García, Almudena Fernández. nternational Pigment Cell Conference (IPCC). Singapore