Melanin is an important pigment-producing compound that determines skin and hair color. Deficiency of melanin can lead to several disorders and diseases. For example, a complete lack of melanin causes a condition called albinism. Melanin deficiency has long been thought to be associated with various genetic abnormalities and birth defects.
Diseases related to melanin include:
albino – There are almost 10 different types of oculocutaneous albinism, which is an autosomal recessive disease. This means that both parents must carry one copy of the mutated gene and the offspring must receive two copies.
The most common form is oculocutaneous albinism type 2, which is particularly common in people of African ethnicity and describes a condition in which melanin in the hair, skin, and eyes is reduced or absent. The incidence of this type of albinism is approximately 1 in 10,000 in African Americans and 1 in 36,000 in white Americans.
In some African countries, the incidence of this type of albinism can reach 1 in 2000.
Another common albinism is yellow oculocutaneous albinism, which is observed in Germans or Swiss people. These people have white hair and fair skin at birth, but may develop normal pigmentation as they reach infancy and childhood.
Melanin deficiency is also associated with hearing loss. For example, in Waardenburg syndrome, which is most common among the Hopi people of North America, loss of pigmentation and hearing loss occur together. The prevalence of this syndrome among the Hopi Indians is approximately 1 in 200 people.
Parkinson’s disease, a neurodegenerative disease, is associated with a lack of neuromelanin in brain regions called the substantia nigra and locus coeruleus. This is thought to result from a decrease in dopaminergic pigment neurons leading to decreased dopamine synthesis in the brain.
Nicotine has a high affinity for melanin-containing tissues and is a precursor for melanin synthesis. This is thought to be related to the reason why people with darker skin are more dependent on nicotine and have lower quit rates.
