Albinism is caused by a lack of the pigment melanin, which usually gives the hair, skin and eyes their colour.
In people with albinism, the cells that make melanin do not work due to genetic mutations (faulty genes).
Different genes are responsible for the different types of albinism.
Oculocutaneous albinism (OCA)
Oculocutaneous albinism (OCA) is the most common type of albinism. Several different genes have been identified that may cause OCA.
Mutations (changes) in different genes cause different types of OCA. For example:
- OCA1A and OCA1B are caused by mutations in the tyrosinase gene
- OCA2 is caused by mutations in the P gene
- OCA3 is caused by mutations in the TRP-1 gene
- OCA4 is caused by mutations in the SLC45A2 gene
How OCA is inherited
OCA is an autosomal recessive condition. This means you need to inherit two copies of the faulty gene (one from your mother and one from your father) to have the condition.
It is estimated that about one in 70 people carry the gene that causes OCA. Carriers of the gene are not affected by the condition and have a normal amount of melanin. If both parents carry the gene, there is a one in four chance their child will have albinism.
Ocular albinism (OA)
There are two types of ocular albinism (OA). These are caused by different genes and are also inherited in different ways:
- OA1 is caused by a mutation in the GPR143 gene
- autosomal recessive ocular albinism (AROA) is caused by mutations in either the tyrosinase gene or the P gene
An adult or child diagnosed with albinism may be referred for genetic counselling. This is a discussion with a geneticist (a healthcare professional trained in the science of human genetics).
The genetic counsellor may be able to explain in more detail what has caused the particular type of albinism and how the condition was inherited.
Read more about genetic testing and counselling.