DETECTION OF FETAL HLA-DQ-ALPHA SEQUENCES IN MATERNAL BLOOD - A GENDER-INDEPENDENT TECHNIQUE OF FETAL CELL IDENTIFICATION

The objective of this study was to detect fetal HLA-DQa gene sequences in maternal blood. HLA-DQa genotypes of 70 pregnant women and their p artners were determined for type A1. We specifically sought couples wh ere the father, but not the mother, had genotype A1. In 12 women, mate rnal blood samples were flow-sorted. Candidate fetal cells were isolat ed and amplified by using PCR primers specific for a paternal HLA-DQa A1 allele. Fetal HLA-DQa A1 genotype was predicted from sorted cells; amniocytes or cheek swabs were used for confirmation. Six of twelve so rted samples had amplification products indicating the presence of the HLA-DQa A1 allele; 6/12 did not. Prediction of the fetal genotype was 100 per cent correct, as determined by subsequent amplification of am niocytes or cheek swabs. We conclude that paternally inherited uniquel y fetal HLA-DQa gene sequences can be identified in maternal blood. Th is system permits the identification of fetal cells independent of fet al gender, and has the potential for non-invasive prenatal diagnosis o f paternally inherited conditions.