Anhydrotic dysplasia is a genetic disorder in humans that results in the absence of sweat glands in the skin. some men have this defect all over their bodies, but in women it is usually expressed in a peculiar way. women with this disorder typically have small patches of skin with sweat glands and other patches without sweat glands. this pattern of sweat-gland distribution can be explained by

This pattern of sweat-gland distribution can be explained by X chromosome inactivation

Explanation:

Women are XX and men are XY, to compensate the genetic information (that women do not have twice as much X information as men), one of these two women's X chromosomes is inactive. X-inactivation occurs during the embryonic process and is random. That is, in some cells one of the Xs can be inactivated, and in other cells the other X can be inactivated. Each of these few embryonic cells will lead to more cells, which will have the same inactive X chromosome as it. Then, in the heterozygous females a mosaic pattern may remain, because in each cell there will be an inactive X chromosome. The anhydrotic dysplasia is linked to the X chromosome, heterozygous women will have some areas in the skin in which cells have inactivated the X chromosome that carries the allele that determines they will have the genetic disorder. In other areas of the skin, the cells will have inactivated the X chromosome that carries the allele that determines they do not have the disease.