Metatropic dysplasia

Metatropic dysplasia (also known as metatropic dwarfism) is a rare skeletal dysplasia characterized by a distinctive change in body proportions over time — infants may appear to have a long trunk and short limbs, but as the child grows, progressive kyphoscoliosis develops, causing the trunk to shorten relative to the limbs. The name 'metatropic' derives from the Greek word for 'changing,' reflecting this shift in proportions. The condition is caused by mutations in the TRPV4 gene, which encodes a calcium-permeable ion channel important for cartilage and bone development. Key clinical features include severe platyspondyly (flattened vertebral bodies), dumbbell-shaped long bones with prominent metaphyseal flaring, a narrow thorax, short limbs with joint enlargement and limited mobility, and a characteristic coccygeal tail-like appendage in some patients. Progressive kyphoscoliosis is a hallmark and can become severe, potentially leading to respiratory compromise. Some patients may also develop cervical spine instability, which can result in spinal cord compression. The clinical spectrum ranges from a severe, lethal neonatal form to milder presentations compatible with survival into adulthood, though significant short stature and skeletal deformity are typical. There is currently no cure or disease-specific therapy for metatropic dysplasia. Management is supportive and multidisciplinary, focusing on orthopedic interventions for kyphoscoliosis (including bracing and spinal surgery when indicated), monitoring for cervical spine instability, respiratory support when needed, and physical therapy to maintain mobility. Regular surveillance by orthopedic, pulmonary, and neurological specialists is recommended. Genetic counseling is important for affected families.

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