Alloanti‐D in a DBT pregnant woman responsible for hemolytic disease of the fetus and newborn: Molecular study and genetic counseling

Abstract Background While some partial D patients are not detected in routine D typing due to strong positive reactions with the commercially available anti‐D reagents used, clinically significant alloanti‐D against the absent epitopes can be produced following immunization with D‐positive (D+) erythrocytes. This study aimed to characterize the allelic variant underlying the D+ phenotype in an alloimmunized, pregnant woman (anti‐D titer: 64) and to provide genetic counseling to her close family members. Materials and Methods The proband and five family members were investigated in the study. Standard hemagglutination techniques were used in phenotyping and titration studies. A quantitative multiplex PCR of short fluorescent fragments (QMPSF) strategy was performed for RH genotyping. Results Our investigation revealed that the proband genotype was RHD*14.02 / RHD*01N.01 responsible for a partial D phenotype, that is, DBT. QMPSF analysis showed that the father and one of her brothers were heterozygous for RHD*14.02 / RHD*01 . The newborn presented with signs and symptoms of hemolytic disease of the fetus and newborn (HDFN), requiring medical intervention. Discussion The RHD variant identified in the maternal sample was responsible for a partial D phenotype. This case highlights the limitations of routine serologic typing for the D antigen, which misidentified a partial D phenotype as D+, preventing the patient from receiving appropriate prophylactic RhIg treatment. Interestingly, the QMPSF‐based strategy resulted in a simple, reliable, and effective method for a relevant allele characterization in all family members. Noteworthy, genetic counseling was provided to the proband's brother carrying the RHD*14.02 variant at the heterozygous state with an RHD*01 allele.