HSPG2 and Schwartz-Jampel syndrome: Mutations in the perlecan gene (HSPG2) have been identified in two classes of musculoskeletal conditions in the relatively mild Schwartz-Jampel syndrome and more severe but relatively rare neonatal lethal dyssegmental dysplasia, Silverman-Handmaker type (Arikawa-Hirasawa et al., 2001a; Arikawa-Hirasawa et al., 2001b; Arikawa-Hirasawa et al., 2002a).