Based on genetic characterization and the way of inheritance, albinism is classified into the following types:
Oculocutaneous Albinism (OCA)
It is the most common type of albinism in which a person is inherited two copies of abnormal genes (one from each parent). These genetically mutated genes (OCA1 to OCA7) alter the melanin production in the hair, skin, and eyes. Mutation in any of the seven OCA genes is sufficient for causing oculocutaneous albinism. Based on the type of genetic defect and degree of melanin production, oculocutaneous albinism is further classified into several types and subtypes.
For example, Oculocutaneous albinism A1 is mainly caused due to a genetic defect in the tyrosinase enzyme and is further categorized into two subtypes OCA1a (complete loss of melanin) and OCA1b (little production of melanin).
Ocular albinism is a less common type of albinism that is limited to the eyes and is associated with vision problems. People suffering from ocular albinism have normal hair and skin pigmentation but no coloring in the retina. It is an X-linked hereditary disorder and is caused due to genetic mutations on the X chromosome. This type of albinism is more common in males as compared to females.
Several rare hereditary conditions such as Hermansky-Pudlak syndrome, Chediak-Higashi syndrome, and Griscelli syndrome are associated with albinism. However, such conditions are very rare and occur due to mutations in albinism-related genes.