Schwartz-Jampel syndrome

Schwartz-Jampel syndrome, abbreviated SJS and also known as chondrodystrophic myotonia, is a rare genetic disease. It is caused by a mutation in the perlecan gene, HSPG2, and produces osteochondrodysplasia, a disorder of bone and cartilage growth, associated with myotonia, which is delayed relaxation of muscle after contraction. Most people with the syndrome have a nearly normal life expectancy. The short source lead supports only these points, so the account here is intentionally brief.