Study of the molecular structure of haplotype RH carrier of the allele RHD*weak D type 4

PRINCIPI C; TRUCCO BOGGIONE C; MUFARREGE N; LUJÁN BRAJOVICH M; MATTALONI S; ENSINCK A; GARCÍA BORRÁS S; BIONDI C; COTORRUELO C

Rosario

Congreso; XX Congreso y XXXVIII Reunión Anual de la Sociedad de Biología de Rosario; 2018

Sociedad de Biología de Rosario

The Rh blood group system is highly polymorphic and has a great clinical interest in Transfusion Medicine due to the participation of its antibodies in the processes of immune destruction of the transfused red blood cells. The RH locus consists of two homologous genes, RHD and RHCE. More than 400 alleles have been reported that generate Rh variant epitopes (partial and/or weak) and phenotypes lacking high prevalence antigens. The RH genes segregate as haplotypes and some RHD and RHCE alleles show genetic linkage disequilibrium. The coexistence of aberrant allelic variants in cis in patients who are under therapy with chronic transfusions may be responsible for delayed transfusion hemolytic reactions due to the production of complex alloantibodies. Molecular studies allow the characterization of the allele involved in the altered expression of Rh antigens, optimizing transfusional compatibility. The aim of this work was to characterize the molecular structure of the RHhaplotype carrying the allelic variantRHD*WeakD type 4. Serologic and molecular analyses were performed in 39 blood samples carryng the RHD*Weak D type 4alelle. The samples were obtained from unrelated patients from different health effectors of our country. D phenotype was investigated by haemagglutination with 4 anti-D monoclonal reagents: IgM / IgG (clones TH28 / MS26), IgM (clone MS201), IgM (clone RUM1) and IgM (clones LDM1 and ESD1M). The complete Rh phenotype was also studied with anti-C (clone MS24), anti-c (clone MS33), anti-E (clone MS258 / MS80) and anti-e (clones MS16 + MS21 + MS63) antibodies. Genomic DNA was obtained using the salting-out method. PCR-SSP strategiesallowed the detection ofc.733G, c.48C and c.48G polymorphisms in the RHCE gene. Serologic analysis in all samples showed a weak D antigen expression and the presence of the c and e antigens only (complete Rh phenotype: Dweak type 4ccee). In 36 (92.31%) samples aberrant RHCE alleles were detected: 27 (75.00%) RHCE*ce(733G, 48C, 48G), 7 (19.44%) RHCE*ce(733G, 48G) and 2 (5.56%) RHCE*ce(733G, 48C). The RHD*Weak D type 4allele is responsible for a partial D phenotype whereas the c.733G and c.48C mutations present in RHCE originate c and e partial antigens. The molecular characterization of the RHD-RHCE haplotype in patients carrying the RHD*Weak D type 4allele results useful to determinetransfusional compatibility and avoid potential anti-D, anti-c or anti-ealloimmunization, mainly in patients who carryRHCE*Ce,RHCE*cE orRHCE*ce(733G, 48C) alleles in trans and require chronic transfusion therapy for the treatment of their primary pathology.