What are the genetic changes related to Dowling-Degos disease ?
Mutations in the KRT5 gene cause Dowling-Degos disease. The KRT5 gene provides instructions for making a protein called keratin 5. Keratins are a family of proteins that form the structural framework of certain cells, particularly cells that make up the skin, hair, and nails. Keratin 5 is produced in cells called keratinocytes found in the outer layer of the skin (the epidermis). Keratin 5 is one component of molecules called keratin intermediate filaments. These filaments assemble into strong networks that help attach keratinocytes together and anchor the epidermis to underlying layers of skin. Researchers believe that keratin 5 may also play a role in transporting melanosomes, which are cellular structures that produce a pigment called melanin. The transport of these structures into keratinocytes is important for normal skin coloration (pigmentation).  KRT5 gene mutations that cause Dowling-Degos disease lead to a decrease in the amount of functional keratin 5 protein that is produced. A reduction in keratin 5 can impair the formation of keratin intermediate filaments. As a result, the normal organization of the epidermis is altered, leading to the development of different types of skin lesions. Additionally, a decrease in keratin 5 may disrupt the movement of pigment-carrying melanosomes into keratinocytes, where they are needed for normal skin pigmentation. This disruption of melanosome transport is thought to cause the pigmentation abnormalities seen in individuals with Dowling-Degos disease.  Some people with Dowling-Degos disease do not have an identified mutation in the KRT5 gene. In these cases, the cause of the condition is unknown.