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- Title
Two New Alleles of the RHCE Gene Found in Caucasian Individuals.
- Authors
Noizat-Pirenne, F.; Le Pennec, P.; Ansart-Pirenne, H.; Aznar, R.; Mouro, I.; Rouzaud, A.; Roussel, M.; Rouger, P.; Catron, J.
- Abstract
Background: Depressed expression of C or both C and e is not a rare problem in the Caucasian population. The CeVA allele associated to these defects is characterized by the replacement of the exon 5 of the RHCe allele by the specific D exon 5. At the serological level, this variant is detected based on the positive reactivity with the Mol serum that contained antibodies against low frequency antigens (RH8,RH30,RH32,RH33,RH50) and on a specific pattern of reactivity with a panel of anti-e monoclonal antibodies. Molecular alteration is confirmed by sequencing the exon 5 of the RHCe allele. Using that procedure, we found 2 new variants that bring questions regarding epitopes of some low frequency antigens. Methods and results: RBCs from 2 Caucasian individuals (samples I and 2) were studied. Previous authors reported for these 2 samples a decreased expression of both C and e antigens and the presence of a low frequency antigen detected by Mol serum (RH50: FPTT). We found that these RBCs reacted similarly as CeVA variants when tested with anti-e MoAbs but only sample 1 was positive with Mol serum. The eluate obtained by adsorption-elution of Mol serum on DFR RBCs (that express RH50) gave positive results with sample 1 and CeVA variants. Therefore, it is likely that sample 1 and CeVa variants express both the RH50 antigen. Sample 2 expressed the RH20 low frequency antigen. Reactivity with antiC MoAbs was different for all 3 variants (samples 1, 2 and CeVA variants). Sequencing of exon 5 exhibited replacements of some CE specific nucleotides by the equivalent D specific nucleotides: G667T,C697G,A712G for sample 1;C697G,C733G,T744C for sample 2. Conclusions: Firstly, the RH50 expression is the result of at least 3 specific D amino-acids surrounded by CE residues within exon 5 as exhibited by sample 1 (F223, E233, V238). The replacement of the entire exon 5 by the equivalent D exon 5 (as in CeVA) is therefore not necessary to induce RHS0 expression. Secondly, we showed that RH20, classically expressed by Black individuals may be expressed by Caucasian individuals as long as the C733G mutation leading to a L245V substitution is present. But, as shown by this study and by other authors, when C733G is present, only some patterns of mutations may induce the expression of RH20.
- Subjects
GENES; EXONS (Genetics); CAUCASIAN race
- Publication
Transfusion, 2001, Vol 41, p4S
- ISSN
0041-1132
- Publication type
Article