Poliosis is a condition where there is a lack of melanin pigment in the hair. It can affect any area of the body that has hair, but it most commonly affects the scalp. Poliosis can be acquired or genetic.
If poliosis is acquired, it is usually due to an injury or disease that damages the melanocytes, which are the cells that produce melanin. Acquired poliosis can also be caused by certain medications or chemicals that damage the melanocytes.
If poliosis is genetic, it is usually due to a mutation in a gene involved in melanin production. The most common form of genetic poliosis is called Waardenburg syndrome, which is caused by a mutation in the PAX3 gene. Waardenburg syndrome can also cause other abnormalities, such as hearing loss and changes in skin pigmentation.