title: Identification of a novel B variant allele at the ABO locus in Chinese Han individuals with B subgroup.
abstract: We studied the molecular genetic background of the B subgroup in the Chinese Han population and identified a novel allele at the ABO locus. Ten control samples from randomly selected blood donors of normal B phenotype and 6 samples from individuals diagnosed as B subgroup by serological tests were genotyped by PCR-SSP and direct DNA sequencing at exons 6 and 7 of the ABO gene. Exons 6 and 7 and the intervening intron 6 of B alleles from the 6 B subgroup samples were analyzed by cloning and haplotype-sequencing. A novel B variant allele was identified in 2 individuals who were serologically-determined as members of the B(x) and B(w) subgroups, respectively. The novel B allele differs from allele B101 by a single 695T>C missense mutation in exon 7. The family of the individual with B(x) subgroup was studied; among 8 family members tested, 4 had the novel B variant allele. No mutation at exon 6 or 7 of the ABO gene was detected in the 10 control samples or in the other 4 B subgroup samples. Mutation at position 695 where T is replaced by C results in an amino acid change from Leu to Pro, which is predicted to diminish B transferase activity. This indicates that alteration of the amino acid at position 232 is critical to the activity of glycosyltransferases.
authors.affiliation: Shen-Zhen Blood Center, Shen-Zhen Institute of Transfusion Medicine, Ni-Gang Xi Road, Mei-Gang Nan Street, Shen-Zhen, Guang-Dong Province, 518035, People's Republic of China. zhihui_deng@yahoo.com.cn
authors.forename: Zhi-Hui
authors.initials: ZH
authors.lastname: Deng
authors.forename: Qiong
authors.initials: Q
authors.lastname: Yu
authors.forename: Yan-Lian
authors.initials: YL
authors.lastname: Lian
authors.forename: Guo-Guang
authors.initials: GG
authors.lastname: Wu
authors.forename: Yu-Qing
authors.initials: YQ
authors.lastname: Su
authors.forename: Xuan
authors.initials: X
authors.lastname: Zhang
mesh_terms: D000017:ABO Blood-Group System / Q000235:genetics*; D000483:Alleles; D044466:Asian People / Q000235:genetics*; D001483:Base Sequence; D001788:Blood Grouping and Crossmatching; D002681:China / Q000208:ethnology; D003001:Cloning, Molecular; D005838:Genotype; D006023:Glycoproteins / Q000235:genetics / Q000378:metabolism; D006801:Humans; D008969:Molecular Sequence Data; D010375:Pedigree; D010641:Phenotype; D012698:Serologic Tests
chemical_list: D000017:ABO Blood-Group System; D006023:Glycoproteins