Novel RHD mutation resulting in an amino acid substitution in the first extracellular loop of the Rhesus protein. RHD p.Y34N

Numerous RHD alleles associated with quantitative (week D) or qualitative (partial D) D antigen variants are reported. Here we describe a novel RHD allele identified in a female patient showing a week Rhesus D phenotype by routine blood grouping. Serologic Rh typing was performed by standard gel card matrix techniques (Bio-Rad). Molecular genetic analysis included genotyping using sequence specific primers (Innotrain) and sequencing of the RHD gene. Genotyping remained inconclusive, however, sequencing analysis identified a missense mutation in exon 1 of the RHD gene (c.100T>A, p.34Tyr34Asn). The novel gene variant results in an amino acid substitution in one of the extracellular domains of the mature protein and may be responsible for the reduced expression of the Rhesus D protein. The presence of a partial D variant susceptible to anti-D alloimmunization following transfusion may not be excluded.