Vitiligo is a long term skin condition characterized by patches of the skin losing their pigment.[1] The patches of skin affected become white and usually have sharp margins. The hair from the skin may also become white.[1] Inside the mouth and nose may also be involved.[2] Typically both sides of the body are affected.[1] Often the patches begin on areas of skin that are exposed to the sun. It is more noticeable in people with dark skin.[2] Vitiligo may result in psychological stress and those affected may be stigmatized.[1]

The cause is typically unknown.[1] It is believed to be due to genetic susceptibility that is triggered by an environmental factor such that an autoimmune disease occurs.[1][2] This results in the destruction of skin pigment cells. Risk factors include a family history of the condition or other autoimmune diseases, such as hyperthyroidism, alopecia areata, and pernicious anemia.[2] Vitiligo is classified into two main types: segmental and non-segmental. Most cases are non-segmental meaning they affect both sides and typically get worse with time. About 10% of cases are segmental meaning they mostly involve one side of the body and do not typically worsen with time.[1] Diagnosis can be confirmed by tissue biopsy.[2]

There is no known cure for vitiligo. For those with light skin, sunscreen and makeup is all that is typically recommended.[1] Other treatment options may include steroid creams or phototherapy to darken the light patches. Or efforts to lighten the unaffected skin, such as with hydroquinone, may be tried. A number of surgical options are available for those who do not improve with other measures.[2] A combination of treatments generally has better outcomes.[3] Counselling to provide emotional support may be useful.[1]

Globally about 1% of people are affected by vitiligo.[3] Some populations have rates as high as 2–3%.[4] Males and females are equally affected. About half show the disorder before age 20 and most develop it before age 40. Vitiligo has been described since ancient history.[1]

CAUSES
Although multiple hypotheses have been suggested as potential triggers that cause vitiligo, studies strongly imply that changes in the immune system are responsible for the condition.[6][14] Vitiligo has been proposed to be a multifactorial disease with genetic susceptibility and environmental factors both thought to play a role.[6]

The TYR gene encodes the protein tyrosinase, which is not a component of the immune system, but is an enzyme of the melanocyte that catalyzes melanin biosynthesis, and a major autoantigen in generalized vitiligo.[6] Some state that sunburns can cause the disease but there is not good evidence to support this.[15]

Immune Edit
Variations in genes that are part of the immune system or part of melanocytes have both been associated with vitiligo.[6] It is also thought to be caused by the immune system attacking and destroying the melanocytes of the skin.[16] A genomewide association study found approximately 36 independent susceptibility loci for generalized vitiligo.[17]

Autoimmune associations Edit
Vitiligo is sometimes associated with autoimmune and inflammatory diseases such as Hashimoto's thyroiditis, scleroderma, rheumatoid arthritis, type 1 diabetes mellitus, psoriasis, Addison's disease, pernicious anemia, alopecia areata, and systemic lupus erythematosus.[6]

Among the inflammatory products of NALP1 are caspase 1 and caspase 7, which activate the inflammatory cytokine interleukin-1β. Interleukin-1β is expressed at high levels in patients with vitiligo.[citation needed] In one of the mutations, the amino acid leucine in the NALP1 protein was replaced by histidine (Leu155->His). The original protein and sequence is highly conserved in evolution, and is found in humans, chimpanzee, rhesus monkey, and the bush baby. Addison's disease (typically an autoimmune destruction of the adrenal glands) may also be seen in individuals with vitiligo.[18][19]