Focal dermal hypoplasia (FDH) is an ectodermal dysplasia, one of a group of disorders that affect the outer layer of the developing embryo. This layer, called the embryonic ectoderm, develops into many parts of a baby's body, including the eyes, skin, teeth, and bones. In ectodermal dysplasias, these parts do not develop normally.
The main symptoms associated with FDH are skin problems, which may include streaks or lines of tumorlike growths on various parts of the body. These are usually present at birth but may develop over time. Older patients with FDH may have pain associated with skin problems. Other symptoms may affect the urinary, digestive, cardiovascular, and central nervous systems.
FDH is caused by a mutation or defect in the PORCN gene. While the exact function of this gene is unknown, activity of the PORCN gene has been detected in the long bones, facial bones, fingers, toes, and teeth. About 90% of cases of FDH are inherited or passed down among family members. FDH is inherited as an X-linked dominant trait.
FDH is a rare condition, with only about 200 to 300 known cases worldwide. The exact incidence of the disorder is unknown. No racial or ethnic group is affected more than any other.
About 90% of people with FDH are female. Males with FDH generally die before birth. Individuals who are severely affected by FDH may die in infancy. Those who are mildly affected may have a normal life expectancy.
Anhidrosis, combined mesoectodermal dysplasia, DHOF, ectodermal and mesodermal dysplasia congenital, ectodermal and mesodermal dysplasia with osseous involvement, FDH, focal dermal dysplasia syndrome, focal dermato-phalangeal dysplasia, FODH, Goltz syndrome, Goltz-Gorlin syndrome, PORCN gene.