Multicentric carpo-tarsal osteolysis with or without nephropathy

Multicentric carpo-tarsal osteolysis with or without nephropathy (also known as multicentric osteolysis, nodulosis, and arthropathy, or MONA; idiopathic multicentric osteolysis; or hereditary multicentric osteolysis) is a rare skeletal disorder characterized by progressive destruction (osteolysis) of the carpal bones (wrist) and tarsal bones (ankle), often beginning in early childhood. The condition primarily affects the musculoskeletal system, leading to pain, swelling, and progressive loss of bone in the hands and feet, which can result in significant functional impairment and deformity. Joint contractures, osteoporosis, and subcutaneous nodules may also develop. In many patients, the disease is accompanied by a progressive nephropathy (kidney disease) that can lead to proteinuria and, in severe cases, end-stage renal failure. The condition is caused by mutations in the MAFB gene, which encodes a transcription factor involved in bone and kidney development. The skeletal manifestations typically present in early childhood, with wrist and ankle swelling being among the first signs noticed by families. Radiographic imaging reveals progressive osteolysis of the carpal and tarsal bones, and in some cases, other bones may also be affected. Kidney involvement varies in severity and may not be present in all affected individuals, hence the designation 'with or without nephropathy.' There is currently no cure for multicentric carpo-tarsal osteolysis. Treatment is primarily supportive and symptomatic, focusing on pain management, physical therapy to maintain joint function, orthopedic interventions for skeletal deformities, and nephrology care for those with kidney involvement. Renal transplantation may be necessary in patients who progress to end-stage kidney disease. Regular monitoring of kidney function is recommended for all affected individuals. Bisphosphonates and anti-inflammatory medications have been tried with variable results.

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