HSPG2 and skeletal dysplasia: Schwartz-Jampel syndrome is an autosomal recessive disorder, caused by homozygous or compound heterozygous mutations in HSPG2, and characterized by permanent myotonia and skeletal dysplasia including a short stature, kyphoscoliosis, bowing of the diaphysis, and irregular epiphyses (Table 6; Nicole et al., 2000; Arikawa-Hirasawa et al., 2002; Stum et al., 2006).