Albinism: Genetics

Abstract

Albinism has classically been described as the complete absence of melanin pigment in the skin, hair and eyes throughout the life of the affected individual. Modern molecular analysis has shown that albinism is a much more complex genetic disorder than previously thought, involving many genes with an array of functions, as well as great variation in the phenotype of affected individuals. There are currently 15 genes that have been associated with albinism, including four nonsyndromic forms of oculocutaneous albinism (reduced pigment affects skin, hair and eyes), one nonsyndromic form of ocular albinism (reduced pigment affects eyes only) and ten syndromic disorders that include albinism as part of the phenotype. The gene functions of the nonsyndromic forms are thought to be involved in melanin biosynthesis and many of the genes associated with the syndromic forms are involved in protein trafficking. Common genetic variants within some of these genes are also associated with normal variation in eye, hair and skin colouration.

Key Concepts:

• All animals make melanin as the chief form of colouration.

• Melanin is made in specific cells called melanocytes.

• Albinism is caused by an absence of melanin biosynthesis resulting in several clinical features.

• There are many different types of albinism.

• There are several genes associated with albinism.

• The molecular pathology of albinism is complex and involves different types of mutations.

• Variation in skin pigmentation involves common polymorphisms in some albinism-related genes.

• Albinism can affect interactions between individuals and society.