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E variants found in Japanese and c antigenicity alteration without substitution in the second extracellular loop
Author(s) -
Kashiwase Kouichi,
Ishikawa Yoshihide,
Hyodo Hironobu,
Watanabe Yoshihisa,
Ogawa Atsuko,
Tsuneyama Hatsue,
Toyoda Chizu,
Uchikawa Makoto,
Akaza Tatsuya,
Omine Mitsuhiro,
Juji Takeo
Publication year - 2001
Publication title -
transfusion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.045
H-Index - 132
eISSN - 1537-2995
pISSN - 0041-1132
DOI - 10.1046/j.1537-2995.2001.41111408.x
Subject(s) - exon , antigenicity , genetics , gene , biology , microbiology and biotechnology , rh blood group system , complementary dna , allele , coding region , polymorphism (computer science) , epitope , antibody
BACKGROUND: The molecular basis of E variants in the Japanese population is poorly understood. In this study, molecular analysis of E variants detected in Japanese by serologic methods was carried out. STUDY DESIGN AND METHODS: E variants from healthy Japanese blood donors were screened by serologic analysis using E MoAbs. Fifteen E variant samples were divided into three types—EFM, EKH, and EKK—on the basis of patterns of reactivity with five distinct E antibodies. The entire coding region of the Rh cDNAs from the E variant samples was analyzed by sequencing. RESULTS: Although the Rh cDNA sequences of the three types were different from each other, those of the EFM‐type variants ( RHEFM ) had a partial DNA exchange in exon 5 between the RHCE and RHD genes, generating an RHcE variant (Gln233Glu, Met238Val). The cDNA of EKH‐type variants ( RHEKH ) exhibited a point mutation (G461C) in exon 3 of the RHcE allele that resulted in an Arg154Thr substitution in the third external loop of the RhcE peptide. The EKK‐type variant ( RHEKK ) carried a hybrid gene structure characterized by replacement of exons 1‐3 (or 2‐3) of the RHCE gene with those of the RHD gene. The RHD gene of a person possessing an E variant of the EKK type was also a hybrid gene, D–cE(2‐3)–D or cE(1‐3)–D ( RHDKK ). The E variants of types EKH and EKK showed weak c antigenicity. CONCLUSION: In serologic screening of 140,723 Japanese blood donors, 15 were found to possess E variants (0.011%). A new RHCE variant, RHEKH , was identified. On the basis of the variants found in this study, the c antigenicity seemed to be determined not only by Pro‐103 but also by the structure of the third extracellular loop or the amino acids contained in it.