PITFALLS IN THE PRENATAL-DIAGNOSIS OF PEROXISOMAL BETA-OXIDATION DEFECTS BY CHORIONIC VILLUS SAMPLING

Variability in the level of expression of very long chain fatty acids (VLCFAs) is documented in cultured chorionic villus (CV) cells derived from two fetuses, one at risk for an unusual peroxisomal fatty acid b eta-oxidation defect, and the other at risk for the X-linked form of a drenoleucodystrophy (ALD). Cells from early subcultures of chorionic c ells from both cases gave normal values for VLCFA ratios. The results for the fetus at risk for the beta-oxidation defect were interpreted t o indicate that the fetus was not affected; however, at birth, the inf ant was clinically and biochemically affected. In the case of the fetu s at risk for X-linked ALD, although VLCFAs were normal in subculture 1, the levels of these fatty acids increased dramatically in subcultur e 3, suggesting an abnormal fetus. Termination of the pregnancy and su bsequent biochemical and morphological follow-up confirmed that the fe tus was indeed affected by ALD.