A Novel RHD Allele Similar to RHD*DIV.4 with Additional c.1025T>C

Polymorphic RH is one of the most important blood group systems used for transfusion. Use of molecular technologies combined with serological testing help to identify the new RHD variants.

The traditional serological test of blood type was performed for a 28-year-old pregnant female. The result showed a weaker positive reaction result on two different microcolumn gel cards. A molecular genotyping assay was performed to get more information.

The gene sequence study indicated 7 nucleotide changes in exon 7, compared with the reference allele. The third-generation sequencing using the long-read PacBio HiFi system showed these variants were all located in the same haplotype. The variant is replaced by the counterpart from RHCE gene in exon 7 with at least 37 bp. Most of its position was located in the sixth extracellular loop.

A novel RHD allele was identified with 7 missense mutations that is similar to RHD*DIV.4 and likely causes a partial D phenotype.