What are the genetic changes related to autosomal recessive hypotrichosis ?
Autosomal recessive hypotrichosis can be caused by mutations in the LIPH, LPAR6, or DSG4 gene. These genes provide instructions for making proteins that are involved in the growth and division (proliferation) and maturation (differentiation) of cells within hair follicles. These cell processes are important for the normal development of hair follicles and for hair growth; as the cells in the hair follicle divide, the hair strand (shaft) is pushed upward and extends beyond the skin, causing the hair to grow. The proteins produced from the LIPH, LPAR6, and DSG4 genes are also found in the outermost layer of skin (the epidermis) and glands in the skin that produce a substance that protects the skin and hair (sebaceous glands).  Mutations in the LIPH, LPAR6, or DSG4 gene result in the production of abnormal proteins that cannot aid in the development of hair follicles. As a result, hair follicles are structurally abnormal and often underdeveloped. Irregular hair follicles alter the structure and growth of hair shafts, leading to woolly, fragile hair that is easily broken. A lack of these proteins in the epidermis likely contributes to the skin problems sometimes seen in affected individuals.  In some areas of the body, other proteins can compensate for the function of the missing protein, so not all areas with hair are affected and not all individuals have skin problems.