Disease name
Schwartz-Jampel 증후군
 Schwartz-Jampel syndrome

Marker gene
Gene symbol Chromosome location Protein name
HSPG2 1p36.12 Basement membrane-specific heparan sulfate proteoglycan core protein

Prevalence
<1 / 1 000 000

Age of onset
신생아기, 영아기

ICD 10 code
G71.1

MIM number
245160
255800

Synonym
Aberfeld syndrome
Burton disease
Burton skeletal dysplasia
Burton syndrome
Catel-Hempel syndrome
Dysostosis enchondralis metaepiphysaria, Catel-Hempel type
Maladie de Burton
Myotonic chondrodystrophy
Myotonic myopathy, dwarfism, chondrodystrophy, ocular and facial anomalies
Osteo-chondro-muscular dystrophy
SJS
SJS1
Schwartz-Jampel syndrome type 1
Schwartz-Jampel-Aberfeld syndrome

Summary
Schwartz-Jampel syndrome (SJS) is characterised by myotonia and osteoarticular abnormalities. Around 100 cases have been described in the literature so far. The clinical manifestations appear soon after birth. The myotonia results in a characteristic facies with blepharophimosis and a puckered facial appearance. Low-set ears, external ear anomalies and micrognathia have also been reported. Limited joint mobility leads to an unsteady gait. Joint stiffness is progressive, reaching its peak during adolescence. Flattening of the vertebral bodies, hip dysplasia, bowing of the diaphyses and irregular epiphyses are often observed. The clinical picture also includes short stature, hirsutism, myopia and small testes. Transmission is autosomal recessive. The causative gene for SJS, HSPG2 (1p36), encodes perlecan, a major component of the cellular matrix. Electromyography reveals myotonia and the osteoarticular anomalies are visible on radiographs. The perlecan deficiency can be detected by immunocytochemical analysis of skin and muscle biopsies or by analysis of fibroblast cultures. The differential diagnosis should include Stuve-Wiedemann syndrome (see this term), which differs from SJS by the type of skeletal anomalies reported and its more severe early prognosis. Severe forms of congenital myotonia and myotonia associated with sodium channel mutations should also be considered in the differential diagnosis. Treatment of the myotonia is problematic but some studies have suggested that carbamazepine leads to improvement of symptoms. The disease appears to stabilise after adolescence.