No abstract

The frequency of RhD negative in Omanis is 8.35% but the molecular background explaining this phenotype is unknown in this population. The RhD negative phenotype has a high molecular diversity. We describe a case report of serological D negative with existence of complete RHD gene in an Omani blood donor. Molecular analysis of RHD exons showed duplication across the boundary of intron 3 and exon 4. This is a 37 bp insert in RHD exon 4 along with c.609 G>A mutation. We were uncertain if the presence of RHDΨ is homozygous [RHDΨ./ RHDΨ.] or hemizygous [RHDΨ./del]. Therefore, molecular basis of D zygosity determination would be a good approach to further explore the case.

RHD variants are divided into three categories; weak D, partial D, and Del. The variants detection is important during donor testing and pregnancy. Studies shown that the detection of D variants may be missed by standard serologic methods including Indirect Antihuman Globulin Test and may cause anti-D immunization when exposed to D-negative individual. The limitations of serology can be overcome by RHD gene molecular typing. We describe for the first time a possible novel DBS-0 like allele partial D which revealed serological D and E negative in an Omani donor that is different from the previously described DBS-0 with serological positive D and partial E.