Acromesomelic dysplasia, Hunter-Thompson type

Acromesomelic dysplasia, Hunter-Thompson type (also known as acromesomelic dwarfism, Hunter-Thompson type) is a rare inherited skeletal disorder characterized by disproportionate short stature primarily affecting the middle (mesomelic) and distal (acromelic) segments of the limbs. The forearms and lower legs are shortened, and the hands and feet are notably small with significant abnormalities of the fingers and toes, including short, stubby digits and malformed or absent bones in the hands and feet. The condition is caused by homozygous or compound heterozygous mutations in the GDF5 gene (also known as CDMP1), which encodes growth/differentiation factor 5, a protein critical for normal skeletal development, particularly in limb formation and joint morphogenesis. Clinical features are typically apparent at birth or in early infancy. Affected individuals show progressive shortening of the limbs with the distal segments most severely involved. The long bones of the forearms (radius and ulna) and lower legs (tibia and fibula) are shortened and may show bowing. The hands demonstrate severe brachydactyly with rudimentary or absent middle and distal phalanges, and the carpal and tarsal bones may be abnormal or fused. Joint mobility may be limited. Importantly, the spine and skull are generally not affected, and intelligence is normal. There is currently no cure or specific treatment for acromesomelic dysplasia, Hunter-Thompson type. Management is supportive and symptomatic, focusing on orthopedic interventions when needed, physical therapy to optimize mobility and function, and monitoring of skeletal development throughout childhood. Genetic counseling is recommended for affected families. The condition follows an autosomal recessive inheritance pattern, meaning both parents must carry a copy of the mutated gene for a child to be affected.

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