Trichorhinophalangeal syndrome type I

Trichorhinophalangeal syndrome type I (TRPS I) is a condition that causes bone and joint malformations; distinctive facial features; and abnormalities of the skin, hair, teeth, sweat glands, and nails. The name of the condition describes some of the areas of the body that are commonly affected: hair (tricho-), nose (rhino-), and fingers and toes (phalangeal).

In people with TRPS I, the ends (epiphyses) of one or more bones in the fingers or toes are abnormally cone-shaped. Additionally, the fingernails and toenails are typically thin and abnormally formed. Affected individuals often have short feet.

Individuals with TRPS I may have a misalignment of the hip joints (hip dysplasia), which often develops in early adulthood but can occur in infancy or childhood. Children with TRPS I often have an unusually large range of movement (hypermobility) in many of their joints. Over time, however, the joints may break down (degenerate), leading to joint pain and a limited range of joint movement.

The characteristic appearance of individuals with TRPS I involves thick eyebrows; a broad nose with a rounded tip; large ears, a long, smooth area between the nose and the upper lip (philtrum); a thin upper lip; and small teeth that are either decreased (oligodontia) or increased (supernumerary) in number. Almost all affected individuals have sparse scalp hair. Males are particularly affected by hair loss with many being nearly or completely bald soon after puberty. Some children with this condition have loose skin, but the skin becomes tighter over time. Individuals with TRPS I may experience excessive sweating (hyperhidrosis).