Langer mesomelic dysplasia

Langer mesomelic dysplasia (also known as Langer mesomelic dwarfism or dyschondrosteosis homozygous type) is a rare skeletal disorder characterized by severe shortening of the limbs, particularly affecting the middle segments (mesomelic segments) — the forearms and lower legs. It is considered the homozygous form of Léri-Weill dyschondrosteosis, meaning affected individuals carry two copies of the disease-causing genetic alteration, typically involving the SHOX (short stature homeobox) gene or its regulatory regions located on the pseudoautosomal region of the X and Y chromosomes. The condition is apparent at birth or during early childhood and results in marked short stature that is more severe than that seen in Léri-Weill dyschondrosteosis. Key skeletal features include severe hypoplasia or aplasia of the ulna and fibula, thickening and bowing of the radius and tibia, and Madelung deformity of the wrist. The mandible may also be underdeveloped (micrognathia). Affected individuals typically have disproportionate short stature with adult height often well below the normal range. Intelligence is generally normal, and internal organs are not typically affected. There is no cure for Langer mesomelic dysplasia. Management is primarily supportive and symptomatic, focusing on orthopedic interventions to address limb deformities and functional limitations. Growth hormone therapy has been considered in some cases, though its efficacy in this condition is not well established. Surgical correction of limb deformities may be necessary to improve function and mobility. Genetic counseling is important for affected families, particularly given the relationship between this condition and Léri-Weill dyschondrosteosis in heterozygous carriers.

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