FDH is a rare disorder that primarily affects females and has extreme variability. It is characterized by skin Lesions that look streaked, underdeveloped or “punched-out”, birth defects of the hands and feet and birth defects of the eyes. There may be inflammation, itching, reddening, blistering, and crusting of the skin. Skin may be absent, discolored or lack color (pigmentation) in some areas. The nails may be absent or appear abnormal. Enlargement of capillaries/veins under the skin (telangectasias) often develop with age. Wart-like growth (papillomas) are usually not present at birth but develop with age and are typically found on the gums, tongue, lips, nose, genetalia, and anus. Overgrowth of tissue may be found on the palms of the hands and soles of the feet. Excessive Sweating (hyperhidrosis) or absence of Sweating (hypohydrosis) is often present on the palms of the hands and soles of the feet. Nearly all individuals with focal dermal hypoplasia display at least a few of the skin abnormalities. The hair may be sparse, brittle, and/or missing.
Eye abnormalities are common and are present at birth and can include: drooping eyelids (ptosis); clouding of the cornea; a cleft or keyhole-shaped defect in the iris or the retina (colobmas); small or missing eye (microphthalmia/anophthalmia); wide spacing between the eyes (hypertelorism); crossed eyes (strabismus); and/or exposure of the lining of the eyelid (ectropion).
Individuals with FDH may also have a variety of skeletal abnormalities, some of which may be present at birth. Curvature of the spine (scoliosis), fused vertebrae, underdeveloped or missing fingers or toes, Extra fingers or toes (polydactyly), fingers or toes that have grown together (syndactyly), fingers that bend to the side (clinodactyly), permanently bent fingers (camptodactyly), and/or fusion of bones of the fingers and toes may be present. Other malformations of the skeleton may include a small skull, an underdeveloped jaw, a forward projection of the jaw, and/or uneven development of the face, limbs, or trunk. Cleft lip and palate may be present and may cause feeding, breathing, and vision problems.
Problems within the mouth are seen in more than 50 percent of patients affected. Failure of the teeth to develop properly often occurs in these patients. The teeth may be missing or underdeveloped and are unusually small or improperly spaced. Missing enamel may aid in the development of cavities.
Abnormalities of the ears, the eyes, the heart, central nervous system, gastrointestinal system, and the kidneys may also be present. Abnormalities within the gastrointestinal system may lead to problems with breathing and feeding. Intellectual disability can be found in some instances. Most patients with FDH are noted to be small at birth and have mild short stature.
An extremely wide range of symptoms characterizes FDH, making it difficult to diagnose.