Fig. 1. QF-PCR results of a chorionic villus sample with placental mosaicism for trisomy 18. (A) Skewed allele ratios in an uncultured chorionic villus sample, demonstrating mosaicism for trisomy 18. (B) Skewed allele ratios in a long-term cultured chorionic villus sample, demonstrating trisomy 18. Allele ratios are shown.

QF-PCR = quantitative fluorescence polymerase chain reaction.