Mondo Description Dyssegmental dysplasia, Silverman-Handmaker type is a rare, genetic, primary bone dysplasia, and lethal form of neonatal short-limbed dwarfism, characterized by anisospondyly, severe short stature and limb shortening, metaphyseal flaring and distinct dysmorphic features (i.e. flat facial appearance, abnormal ears, short neck, narrow thorax). Additional features may include other skeletal findings (e.g. joint contractures, bowed limbs, talipes equinovarus) and urogenital and cardiovascular abnormalities.

Uniprot Description The dyssegmental dysplasias are rare, autosomal recessive skeletal dysplasias with anisospondyly and micromelia. There are two recognized types: the severe, lethal DDSH and the milder Rolland-Desbuquois form. Individuals with DDSH also have a flat face, micrognathia, cleft palate and reduced joint mobility, and frequently have an encephalocoele. The endochondral growth plate is short, the calcospherites (which are spherical calcium-phosphorus crystals produced by hypertrophic chondrocytes) are unfused, and there is mucoid degeneration of the resting cartilage.