Tarsal-carpal coalition syndrome

Tarsal-carpal coalition syndrome (also known as tarsal and carpal coalition syndrome or Nievergelt-Pearlman syndrome in some older literature) is a rare genetic skeletal disorder characterized by fusion (coalition) of the tarsal bones in the feet and carpal bones in the hands. The condition primarily affects the musculoskeletal system, with the hallmark feature being progressive bony fusion of the small bones of the wrists and ankles. Affected individuals typically present with limited range of motion in the hands and feet, which may lead to stiffness, pain, and functional impairment. Additional skeletal features may include short stature, humeroradial fusion (fusion of bones in the forearm and upper arm), and other joint limitations. Some patients may also exhibit brachydactyly (short fingers) and other minor skeletal anomalies. The condition is inherited in an autosomal dominant pattern, meaning that a single copy of the altered gene is sufficient to cause the disorder. Tarsal-carpal coalition syndrome has been linked to mutations in the NOG gene (noggin), which plays a critical role in bone and joint development by regulating bone morphogenetic protein (BMP) signaling. Mutations in this gene can disrupt normal joint formation, leading to the characteristic bony fusions seen in this condition. The disorder typically manifests in childhood, as the progressive fusion of tarsal and carpal bones becomes apparent with skeletal maturation. There is currently no cure for tarsal-carpal coalition syndrome. Treatment is symptomatic and supportive, focusing on managing pain, preserving joint function, and improving quality of life. Orthopedic interventions, including physical therapy and, in some cases, surgical resection of bony coalitions, may be considered to improve mobility. Genetic counseling is recommended for affected families to understand recurrence risks and inheritance patterns.

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