RHIZOMELIC CHONDRODYSPLASIA PUNCTATA TYPE 3 RCDP3

Description: ALKYLDIHYDROXYACETONEPHOSPHATE SYNTHASE DEFICIENCY ALKYLGLYCERONE-PHOSPHATE SYNTHASE DEFICIENCY AGPS DEFICIENCY type 3 rhizomelic chondrodysplasia punctata (RCDP3) is caused by mutations in the alkyldihydroxyacetonephosphate synthase (alkyl-DHAP synthase) gene (AGPS; 603051). Type 1 RCDP (215100) results from a defect in the PEX7 gene (601757). In type 2 RCDP (RCDP2; 222765), there is an isolated deficiency of DHAP acyltransferase (602744). The rhizomelic form of chondrodysplasia punctata (RCDP; 215100) is a peroxisomal disorder. Four peroxisomal abnormalities have been identified in the classic form of RCDP: deficiency of dihydroxyacetonephosphate acyltransferase (DHAPAT) and alkyl-DHAP synthase (EC 2.5.1.26), deficient phytanic acid alpha-oxidation, and an abnormal molecular form of peroxisomal thiolase. Wanders et al. (1994) identified a patient showing all the clinical features of RCDP, including the typical radiologic abnormalities, but lacking the tetrad of biochemical abnormalities found in classic RCDP patients. Instead, an isolated deficiency of alkyl-DHAP synthase was found.