Rhizomelic chondrodysplasia punctata: clinical, pathologic, and biochemical findings in two patients.

The clinical, pathologic, and biochemical features of rhizomelic chondrodysplasia punctata are described in two patients. Although both patients had clinical and radiologic similarities, one patient survived for only 13 days and the other is still alive at 8 years. The most prominent pathologic feature was the marked degenerative change in the chondrocytes from resting cartilage. Fibroblast alkyldihydroxyacetone phosphate synthase activity was markedly reduced in both patients (approximately 10% of control mean); in contrast, dihydroxyacetone phosphate acyltransferase activity was only moderately reduced (50% of control mean). Alkyl and alk-l-enyl ether (plasmalogens) levels were very low in brain and liver. The accumulation of phytanic acid observed in plasma or liver was paralleled by a reduced ability of the patients' fibroblasts to oxidize phytanic acid. Our data indicate that the genetic defect in rhizomelic chondrodysplasia punctata results in abnormalities in two apparently unrelated pathways (i.e., phytanic acid oxidation and ether lipid biosynthesis.