Non-invasive Fetal Genotyping
The Molecular Diagnostics Department of IBGRL undertakes genetic investigation to identify women with antigen-positive fetuses who are at risk of haemolytic disease of the fetus and newborn (HDFN). Upon identification, expecting mothers can then be informed and prepared for further careful monitoring during their pregnancy.The Molecular Diagnostics Department also identifies pregnant women who have antigen-negative fetuses and who therefore are not at danger from HDFN.
The laboratory conducts a fetal sex genotyping service for pregnancies affected by X-linked genetic conditions or when early treatment of the fetus differs according to fetal gender.
A cell-free fetal DNA screening service is also offered for determination of fetal D blood group in D negative pregnant women to guide the requirement for antenatal anti-D prophylaxis. High-throughput non-invasive prenatal testing for fetal RHD genotype is recommended by the National Institute for Health and Care Excellence (NICE) as a cost-effective option to guide antenatal prophylaxis with anti-D immunoglobulin.
Red Cell Genotyping
In multi-transfused patients or DAT positive patients, the presence of transfused red cells or auto-antibodies can prevent determination of blood group phenotype by serological techniques, however analysis of genotype can be used to predict blood group phenotype.
The blood group phenotype of a fetus can be determined by analysis of DNA derived from fetal cells in amniotic fluid of chorionic villus (CV).