Definition:

Schwartz-Jampel syndrome (SJS) is a rare hereditary disorder with joint contractures, generalized myotonia, skeletal anomalies, and facial dysmorphism. Schwartz-Jampel syndrome (SJS) is a term now applied to 2 different autosomal recessive disorder, sometimes termed SJS type 1 and SJS type 2. SJS type 1 results from mutations in the HSPG2 gene, which encodes perlecan, a major component of basement membranes. It exhibits muscle stiffness, mild muscle weakness, and a number of minor morphological abnormalities. In affected patients, problems with motor development frequently become evident during the first year of life. SJS type 2, also known as Stuve-Wiedemann syndrome [DS:H00462], is a genetically distinct disorder with a more severe phenotype.