X-linked spondyloepiphyseal dysplasia tarda is an inherited skeletal disorder that  affects males only. Physical characteristics include moderate short-stature (dwarfism); moderate to severe spinal deformities; barrel-chest; disproportionately short trunk and neck; disproportionately long arms, and premature osteoarthritis, especially in the hip joints. Final male adult height ranges from 4 feet 10 inches to 5 feet 6 inches. Other skeletal features of this condition include decreased mobility of the elbow and hip joints, arthritis, and abnormalities of the hip joint which causes the upper leg bones to turn inward. This condition is caused by mutations in the TRAPPC2 gene and is inherited in an X-linked recessive pattern.

This condition is caused by mutations in the TRAPPC2 gene (sometimes called the SEDL gene), which is located on the X chromosome. The TRAPPC2 gene provides instructions for producing a protein called sedlin. The function of this protein is unclear. Researchers believe that sedlin is part of a larger protein complex, which helps transport proteins between various cell organelles. Mutations in TRAPPC2 affect how the sedlin protein is made, which ultimately affects bone growth.

Many affected individuals require joint replacement surgery (hip, knee, shoulder) or spine surgery (correction of scoliosis or kyphosis). Hip replacement is often required as early as 30 years of age. Chronic pain management is standard and often required before or after surgery. Affected individuals should be regularly followed by a professional familiar with this condition for the development of joint pain and scoliosis.

Affected males usually show signs and symptoms of this condition between 5 and 10 years of age. Progressive joint and back pain usually increases with age. The hips, knees, and shoulder joints are commonly involved to variable degrees. The joints in the hands and feet are usually not affected. Given the skeletal and joint abnormalities seen in this condition, affected individuals are often advised to avoid activities that place undue stress on the spine and weight-bearing joints. Affected males appear to have a normal lifespan and intelligence. Normal motor and cognitive milestones are usually achieved.

This condition is inherited in an X-linked recessive pattern. A condition is considered X-linked if the mutated gene that causes the disorder is located on the X chromosome, one of the two sex chromosomes. In X-linked recessive inheritance, a female with one mutated copy of the gene in each cell is called a carrier. She can pass on the altered gene, but usually does not experience signs and symptoms of the disorder. However, mild symptoms of osteoarthritis have been reported in female carriers of X-linked spondyloepiphyseal dysplasia tarda.