Presence of the RHD pseudogene and the hybrid RHD-CE-D(s) gene in Brazilians with the D-negative phenotype.
The molecular basis for RHD pseudogene or RHD Psi is a 37-bp insertion in exon 4 of RHD. This insertion, found in two-thirds of D-negative Africans, appears to introduce a stop codon at position 210. The hybrid RHD-CE-Ds, where the 3' end of exon 3 and exons 4 to 8 are derived from RHCE, is associated with the VS+V- phenotype, and leads to a D-negative phenotype in people of African origin. We determined whether Brazilian blood donors of heterogeneous ethnic origin had RHD Psi and RHD-CE-Ds. DNA from 206 blood donors were tested for RHD Psi by a multiplex PCR that detects RHD, RHD Psi and the C and c alleles of RHCE. The RHD genotype was determined by comparison of size of amplified products associated with the RHD gene in both intron 4 and exon 10/3'-UTR. VS was determined by amplification of exon 5 of RHCE, and sequencing of PCR products was used to analyze C733G (Leu245Val). Twenty-two (11%) of the 206 D-negative Brazilians studied had the RHD Psi, 5 (2%) had the RHD-CE-Ds hybrid gene associated with the VS+V- phenotype, and 179 (87%) entirely lacked RHD. As expected, RHD was deleted in all the 50 individuals of Caucasian descent. Among the 156 individuals of African descent, 22 (14%) had inactive RHD and 3% had the RHD-CE-Ds hybrid gene. These data confirm that the inclusion of two different multiplex PCR for RHD is essential to test the D-negative Brazilian population in order to avoid false-positive typing of polytransfused patients and fetuses.
Hemocentro, Universidade Estadual de Campinas, Campinas, SP, Brasil. artemisr@bol.com.br
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A
Rodrigues
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Rios
J
J
Pellegrino
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Costa
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Castilho
D044383:Black People / Q000235:genetics; D001782:Blood Donors; D001938:Brazil / Q000453:epidemiology; D005006:Ethnicity / Q000235:genetics*; D005091:Exons; D006801:Humans; D015514:Oncogene Proteins, Fusion / Q000235:genetics*; D010641:Phenotype; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D011544:Pseudogenes / Q000235:genetics*; D011993:Recombinant Fusion Proteins; D012204:Rh-Hr Blood-Group System / Q000235:genetics*; D017421:Sequence Analysis; D017422:Sequence Analysis, DNA; D044465:White People / Q000235:genetics
D015514:Oncogene Proteins, Fusion; D011993:Recombinant Fusion Proteins; D012204:Rh-Hr Blood-Group System; C117760:RhD fusion protein, human; C026410:Rho(D) antigen