Abstracts of the 31st Regional ISBT Congress, ISBT In Focus, Virtual meeting, 2-8 June 2021

PRINCIPI, CINTIA; LUJAN BRAJOVICH, MELINA; BIONDI, CLAUDIA; MUFARREGE, NICOLÁS; ENSINCK, ALEJANDRA; TRUCCO BOGGIONE CAROLINA; MATTALONI, STELLA; COTORRUELO, CARLOS

Vox sanguinis

NLM (Medline)

Año: 2021 vol. 116 p. 5 - 188

Background: RHD*weak D type 1 variant is strongly associated withRHCE*Ce allele on R1 haplotypes. However, previous research conductedin our laboratory showed that in approximately 17% ofArgentineans with weak D type 1 phenotype, the RHD*weak D type 1allele is found on R0 haplotypes. RHCE*Ce and RHCE*CE alleles carry acytosine at nucleotide 48 (c.48C) in RHCE exon 1 while RHCE*ce andRHCE*cE are generally associated to a guanine at position 48 (c.48G).It has been observed that c.48C single nucleotide variation (SNV) isalso found in some RHCE*ce variants (RHCE*ce.01) in the context ofR0 haplotypes.Aims: The aim of this study was to analyse the RHCE polymorphism atnucleotide 48 in Argentinean donors carrying RHD*weak D type 1alleles on R0 haplotypes.Methods: DNA samples from 20 Dweak type 1ccee and 41 Dccee Argentineandonors were investigated. Two PCR procedures each containing forward primers targeting c.48C or c.48G SNVs in RHCE exon 1, respectively,paired with an RHCE intron 1-specific reverse primer were usedto investigate RHCE nucleotide 48 polymorphism. RHD zygosity wasinvestigated by PCR-RFLP. The presence of a hybrid Rhesus box, thatimplies a RHD hemizygous status, was demonstrated by amplificationof the downstream and hybrid Rhesus boxes followed by digestion ofthe PCR products with endonuclease PstI.Results: Molecular analysis allowed the detection of c.48C and c.48Gpolymorphisms in all samples carrying RHD*weak D type 1 alleles onR0 haplotypes (n=20, 100%). On the other hand, 19 of the 41 (46.3%)Dccee samples harboured c.48C and c.48G SNVs while 22 (53.7%)only showed guanine at position 48. All weak D type 1 samples on R0haplotypes were RHD hemizygous and only 1 RHD homozygous samplewas found in the group of Dccee samples, which has both c.48Cand c.48G SNVs.Summary/Conclusions: These results suggest that RHD*weak D type 1alleles is linked to RHCE*ce.01 variant when found on R0 haplotypes.The c.48G>C transversion in RHCE exon 1 leads to p.Trp16Cys, usuallypresent in conventional RHCE*Ce and RHCE*CE alleles, whileTrp16 is associated with RHCE*ce and RHCE*cE alleles. The presenceof Cys16 in RHCE*ce is associated with the R0 haplotype in Africans,leading to a weak e antigen expression on red blood cells. The findingof 46.3% of Dccee samples carrying RHCE*ce.01 alleles can be attributedto African ancestry in the Argentinean population. Geneticrecombination events occurring in such admixed population couldaccount for the strong association between a Caucasian allele(RHD*weak D type 1) and an African allele (RHCE*ce.01) found on R0haplotypes.