SNP Shot: Genomic Insights

Trichorhinophalangeal syndrome type I (TRPS I) is a genetic disorder characterized by skeletal and joint problems, distinctive facial features, and abnormalities affecting the skin, hair, teeth, sweat glands, and nails. The condition's name reflects the body parts most frequently involved: hair (tricho-), nose (rhino-), and fingers and toes (phalangeal).

A hallmark of TRPS I is the presence of cone-shaped epiphyses at the ends of one or more bones in the fingers or toes. Furthermore, the fingernails and toenails are usually thin and malformed. People with TRPS I often have unusually short feet.

Hip dysplasia, a misalignment of the hip joints, can occur in individuals with TRPS I, often developing in early adulthood, though it can appear earlier. Joint hypermobility is common in children with TRPS I. However, over time, joint degeneration can lead to pain and restricted movement.

The facial appearance of those with TRPS I typically includes thick eyebrows, a bulbous nose with a rounded tip, prominent ears, a long, smooth philtrum (the area between the nose and upper lip), a thin upper lip, and dental anomalies such as oligodontia (missing teeth) or supernumerary teeth (extra teeth). Sparse scalp hair is almost universally present. Males are often severely affected by hair loss, with many experiencing significant or complete baldness shortly after puberty. Loose skin may be observed in some children with TRPS I, becoming tighter with age. Excessive sweating, or hyperhidrosis, can also occur.

Inheritance:

TRPS I follows an autosomal dominant inheritance pattern. This means that only one copy of a mutated gene is necessary for the disorder to manifest. In most instances, an affected individual inherits the altered gene from a parent who also has the condition. However, TRPS I can also arise from spontaneous new mutations in the gene, occurring in individuals with no family history of the disorder.