Camptodactyly-arthropathy-coxa-vara-pericarditis syndrome

Camptodactyly-arthropathy-coxa vara-pericarditis syndrome (CACP syndrome), also known as jacknife seizure syndrome or familial arthropathy with camptodactyly, is a rare autosomal recessive disorder caused by mutations in the PRG4 gene located on chromosome 1q25. The PRG4 gene encodes proteoglycan 4 (also known as lubricin), a glycoprotein that plays a critical role in joint lubrication and synovial homeostasis. Loss of functional lubricin leads to the characteristic features of this condition. The syndrome primarily affects the musculoskeletal and cardiovascular systems. Key clinical features include camptodactyly (permanent flexion contractures of the fingers), a non-inflammatory arthropathy with synovial hyperplasia affecting large joints, coxa vara (a hip deformity where the angle between the femoral neck and shaft is reduced), and non-inflammatory pericarditis (inflammation of the pericardial sac surrounding the heart). Camptodactyly is typically the earliest manifestation, often present from infancy or early childhood, while the arthropathy tends to be progressive and can lead to significant joint dysfunction. The pericarditis, when present, may cause pericardial effusion but is generally not life-threatening. There is currently no cure or disease-specific therapy for CACP syndrome. Treatment is supportive and symptomatic, focusing on orthopedic management of joint contractures and deformities through physical therapy, splinting, and in some cases surgical intervention. Pericarditis is managed with standard anti-inflammatory approaches or pericardiocentesis if significant effusion develops. Genetic counseling is recommended for affected families. Research into recombinant lubricin as a potential therapeutic agent is ongoing.

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