Complete sequencing of a genetic polymorphism in NAT2 in the Korean population.

both cultured and uncultured chorionic villi were of fetal origin, (b) the 632C3T transition was heterozygous (Fig. 1B), and (c) the complex I enzyme activities were normal (Table 1). A healthy boy was born after an uncomplicated pregnancy. He is now 3 years of age and does not show any symptoms of mitochondrial disease. This case demonstrates the difficulties that can arise from prenatal diagnosis based on biochemical results alone. When results differ between native and cultured cells, no safe prediction can be made. Unidentified culturing artifacts might influence the biochemical activity of the cultured cells. Especially if the fetal cells are complex I deficient, a few “healthy” maternal cells may overgrow the fetal cells because of their advantage in oxidative energy metabolism. When interpreting the results of biochemical tests on cultured chorionic villi, one should be aware of the possibility of maternal cell contamination and exclude it by microsatellite marker analysis. When the fetus is male, a chromosome analysis might suffice.