Decreased number of melanocytes are seen in: March 2005

Ans. D: All of the above Melanopenic hypopigmentation is due to decrease in number of melanosomes, which could be due to: Genetic diseases-albinism, piebaldism A utoimmune diseases-vitiligo Post-inflammatory-Discoid lupus erythematosus Piebaldism is due to an absence of melanocytes in affected skin and hair follicles. The condition is present at bih and usually remains unchanged throughout life. This is caused by mutations of the KIT proto-oncogene. 14 point mutations, 9 deletions, 2 nucleotide splice mutations, and 3 inseions of the KIT gene are believed to be mutations causing piebaldism. The severity of the condition correlates with the site of the mutation within the KIT gene. Piebaldism is an autosomal dominant genetic disorder meaning half of an affected person's children will also have the condition. Piebaldism is one of the cutaneous signs of Waardenburg syndrome. Piebaldism is a rare inherited condition characterised by: White forelock in 80-90% of those affected (poliosis) White patch (due to absence of pigmentation) of the central poion of the forehead Eyebrow and eyelash hair may also be affected, either continuously or discontinuously with the forelock White patches of skin may also be seen on the face (paicularly the chin), trunk and extremities (hands and feet are not usually affected) Often a narrow border of hyperpigmented skin surrounds the white unpigmented patches Sometimes islands of normal or hyperpigmented skin occur within the white patches. Albinism is a condition in which people have little or no melanin pigment (compound that creates colour) in their eyes, skin or hair. Because of this people with albinism look a little different from other members of their family without albinism. They have very fair skin which is prone to sunburn, their hair is white or a very light colour, and they may squint a lot as their eyes are sensitive to sunlight.