The dyssegmental dysplasia is a rare, autosomal recessive skeletal dysplasia with micromelia. There are two recognized types: the severe, lethal Silverman-Handmaker type (DDSH) and the milder Rolland-Desbuquois type. Individuals with DDSH also have a flat face, micrognathia, cleft palate and reduced joint mobility, and frequently have an encephalocele. DDSH is caused by a functional null mutation of perlecan gene (HSPG2).
