title: Structural and functional mutations of the perlecan gene cause Schwartz-Jampel syndrome, with myotonic myopathy and chondrodysplasia.
abstract: Perlecan, a large heparan sulfate proteoglycan, is a component of the basement membrane and other extracellular matrices and has been implicated in multiple biological functions. Mutations in the perlecan gene (HSPG2) cause two classes of skeletal disorders: the relatively mild Schwartz-Jampel syndrome (SJS) and severe neonatal lethal dyssegmental dysplasia, Silverman-Handmaker type (DDSH). SJS is an autosomal recessive skeletal dysplasia characterized by varying degrees of myotonia and chondrodysplasia, and patients with SJS survive. The molecular mechanism underlying the chondrodystrophic myotonia phenotype of SJS is unknown. In the present report, we identify five different mutations that resulted in various forms of perlecan in three unrelated patients with SJS. Heterozygous mutations in two patients with SJS either produced truncated perlecan that lacked domain V or significantly reduced levels of wild-type perlecan. The third patient had a homozygous 7-kb deletion that resulted in reduced amounts of nearly full-length perlecan. Unlike DDSH, the SJS mutations result in different forms of perlecan in reduced levels that are secreted to the extracellular matrix and are likely partially functional. These findings suggest that perlecan has an important role in neuromuscular function and cartilage formation, and they define the molecular basis involved in the difference in the phenotypic severity between DDSH and SJS.
authors.affiliation: Craniofacial Developmental Biology and Regeneration Branch, National Institute of Dental and Craniofacial Research, Bethesda, MD 20892, USA.
authors.forename: Eri
authors.initials: E
authors.lastname: Arikawa-Hirasawa
authors.forename: Alexander H
authors.initials: AH
authors.lastname: Le
authors.forename: Ichizo
authors.initials: I
authors.lastname: Nishino
authors.forename: Ikuya
authors.initials: I
authors.lastname: Nonaka
authors.forename: Nicola C
authors.initials: NC
authors.lastname: Ho
authors.forename: Clair A
authors.initials: CA
authors.lastname: Francomano
authors.forename: Prasanthi
authors.initials: P
authors.lastname: Govindraj
authors.forename: John R
authors.initials: JR
authors.lastname: Hassell
authors.forename: Joseph M
authors.initials: JM
authors.lastname: Devaney
authors.forename: Jürgen
authors.initials: J
authors.lastname: Spranger
authors.forename: Roger E
authors.initials: RE
authors.lastname: Stevenson
authors.forename: Susan
authors.initials: S
authors.lastname: Iannaccone
authors.forename: Marinos C
authors.initials: MC
authors.lastname: Dalakas
authors.forename: Yoshihiko
authors.initials: Y
authors.lastname: Yamada
mesh_terms: D001483:Base Sequence; D002648:Child; D002675:Child, Preschool; D004252:DNA Mutational Analysis; D005091:Exons / Q000235:genetics; D005838:Genotype; D019812:Heparan Sulfate Proteoglycans / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007223:Infant; D008297:Male; D009154:Mutation / Q000235:genetics*; D020967:Myotonic Disorders / Q000150:complications* / Q000235:genetics* / Q000503:physiopathology; D010009:Osteochondrodysplasias / Q000150:complications* / Q000235:genetics* / Q000503:physiopathology; D010641:Phenotype; D013329:Structure-Activity Relationship
chemical_list: D019812:Heparan Sulfate Proteoglycans; C071927:perlecan