dyssegmental dysplasia—Silverman-Handmaker typeJoe Segen2016-11-25T19:03:43+00:00
dyssegmental dysplasia—Silverman-Handmaker type
Definition A severe lethal form (OMIM:224410) of dyssegmental dysplasia* characterised by flat facies micrognathia, cleft palate, reduced joint mobility, and encephalocoele. The endochondral growth plate is short, calcospherites** are unfused, and there is mucoid degeneration of resting cartilage.
Comments *Dyssegmental dysplasia is a rare, autosomal recessive skeletal dysplasia with anisospondyly and micromelia. There is also the milder Rolland-Desbuquois form. **Spherical calcium-phosphorus crystals produced by hypertrophic chondrocytes.
Molecular pathology Defects of HSPG2, which encodes perlecan, a multidomain proteoglycan that is a major component of basement membranes, where it is involved in stabilising other molecules, cause dyssegmental dysplasia—Silverman-Handmaker type.
Synonyms Anisospondylic camptomicromelic dyssegmantal dwarfism, dyssegmental dwarfism Silverman-Handmaker type