[A novel M142T mutation in the B glycosyltransferase gene associated with B3 variant in Chinese].
OBJECTIVE
To investigate the molecular genetic basis of the B3 variant of ABO blood group system with mixed-field hemagglutination in Chinese.


METHODS
Serological techniques were performed to characterize the erythrocyte phenotype of two discrepant samples. A sequential agglutination method and 13 short tandem repeat (STR) loci were tested to exclude the possibility of exogenous or endogenous DNA chimera. Mutations in exons 6 and 7, including partial intron of the ABO gene, were screened by polymerase chain reaction and DNA sequencing. Haplotypes of the two individuals were also analyzed by sequencing.


RESULTS
A mixed-field hemagglutination of RBCs with anti-B and anti-AB antibodies was detected in the two unrelated individuals. Exogenous ABO-incompatible RBC transfusion and endogenous genetic chimera were excluded by sequential agglutination method and STR. The ABO phenotypes of the two individuals were classified as A1B3 according to the ABO subgroup definition. The sequence region from intron 5 to 3'-UTR of the B allele was identical to that of ABO*B101 allele, except for a T to C substitution at nucleotide position 425 in exon 7. This substitution resulted in an amino acid change of M142T in the B glycosyltransferase.


CONCLUSIONS
A novel B allele with 425T>C substitution resulting in B3 subgroup was identified in two Chinese individuals.
Xu
Xian-guo
XG
Key Laboratory of Blood Safety Research, Ministry of Health, Institute of Transfusion Medicine, Blood Center of Zhejiang Province, Hangzhou, Zhejiang, 310006 PR China.
Hong
Xiao-zhen
XZ
Liu
Ying
Y
Zhu
Fa-ming
FM
Lv
Hang-jun
HJ
Yan
Li-xing
LX
D015061:1,4-alpha-Glucan Branching Enzyme / Q000235:genetics*; D000017:ABO Blood-Group System / Q000235:genetics*; D000483:Alleles; D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D000818:Animals; D044466:Asian People / Q000235:genetics; D002417:Cattle; D004252:DNA Mutational Analysis; D004285:Dogs; D006801:Humans; D008715:Methionine / Q000235:genetics; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D010641:Phenotype; D051381:Rats; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D013912:Threonine / Q000235:genetics
D000017:ABO Blood-Group System; D013912:Threonine; D008715:Methionine; D015061:1,4-alpha-Glucan Branching Enzyme