DSG4

The DSG4 gene provides instructions for making a protein called desmoglein 4 (DSG4). This protein is found in specialized structures called desmosomes that are located in the membrane surrounding certain cells. Desmosomes help attach cells to one another and play a role in communication between cells. The DSG4 protein is found in cells in certain regions of the hair follicle, including the inner compartment of the hair shaft known as the cortex. Desmosomes in these regions provide strength to the hair and are involved in signaling between neighboring cells within the hair shaft. The DSG4 protein may play a role in communicating the signals for cells to mature (differentiate) and form the hair shaft. In addition, the DSG4 protein is found in the upper layers of the skin where it provides strength and communicates signals for the skin cells to mature.

monilethrix - caused by mutations in the DSG4 gene

Mutations in the DSG4 gene have been found in people with monilethrix, a hair condition characterized by strands of hair with a beaded appearance. People with this condition also have short, brittle hair that breaks easily. The mutations associated with this condition affect the extracellular domain of the DSG4 protein, which is the region of the protein outside the cell that interacts with other cells. In people with monilethrix, the cortex of the affected hair shaft appears abnormal. However, it is unclear how mutations in the DSG4 gene are related to the abnormality in the cortex or the beaded appearance of the hair.

other disorders - caused by mutations in the DSG4 gene

Mutations in the DSG4 gene have also been found in people with localized autosomal recessive hypotrichosis. People with this condition have features similar to those of monilethrix, including short, brittle hair, but without the beaded appearance of the hair shaft. It is unclear why an individual develops one condition or the other or whether the two conditions represent different forms of the same disorder.