Certain variants of the RhD antigen in pregnant women could indicate they are at risk of developing hemolytic disease of the fetus and newborn (HDFN), highlighting the importance of including Rhd genotyping in prenatal testing, according to a recently published study in the Journal of Medicine and Life.
After ABO blood group incompatibility, RhD antigen incompatibility is the most common cause of HDFN. Approximately 85% of the population worldwide has a protein known as the RhD antigen in the membrane of their red blood cells and is considered to be RhD-positive.
Women who are RhD-negative and are pregnant with an RhD-positive fetus are at risk of developing antibodies against this antigen. In a subsequent pregnancy, anti-RhD antibodies can cross the placenta and destroy the red blood cells of the fetus, causing what is known as HDFN.
Part of the prenatal test battery consists of testing for RhD. Women who test negative for RhD are candidates for receiving an intravenous treatment called RhD immunoprophylaxis to prevent the development of anti-Rad antibodies capable of causing HDFN. However, some women can not be classified simply as RhD negative or positive and fall into the de Rhd variant category.
RhD variants include weak D and partial D, which can confuse when interpreting prenatal tests and deciding which women should receive RhD immunoprophylaxis.
To assess how frequent these variants are, the authors searched a medical database using keywords such as anti-D alloimmunization and RhD women, leading to the selection of four articles that had the required criteria.
The percentage of mothers with RhD positivity varied greatly between articles, with one reporting a percentage as low as 22% and another as high as 82%. The average percentage of patients with RhD variants was around 15%, but as with RhD positivity, this number varied significantly among studies.
The authors attributed the variance among studies to the challenges in determining RhD variants’ presence.
“These findings highlight the prevalence of serological discrepancies associated with different types of D variants, which can potentially alter the risk of hemolytic disease in the fetus and newborn.” the authors concluded.
