[Molecular study on CisAB and B(A) blood group in Chinese individuals].
OBJECTIVE
This is a study on some ABO subgroup samples which show discordant results of serological and molecular blood typing, the aim is to clarify their true ABO type by means of nucleotide analysis on exons 6 and 7 of their ABO gene.


METHODS
Absorb-elution test and family investigation were conducted to study 7 samples which were involved in ABO grouping discrepancies. Duplex polymerase chain reaction-restriction fragment length polymorphism(PCR-RFLP) method was used to identify their ABO genotypes. PCR products of exons 6 and 7 were cloned and sequenced.


RESULTS
All the 7 ABO subgroup samples with the discordant results of serological and molecular blood typing were found to have the normal O gene. Four out of them were typed as ABsub by serology, they were all of the A*102/O genotype. Sequencing analysis found all their A gene having the nt467 (C-->T) and nt803 (G-->C) mutation by comparison with the A*101 allele, i.e. their real type should be CisAB/O. Three out of 7 were typed as AsubB by serology and as BO by genotype; and point mutation was detected in all of their B gene. One of them had the nt700 (C-->G) mutation, the other 2 unrelated individuals had the novel nt640 (A-->G) mutation in their B alleles.


CONCLUSIONS
Through nucleotide analysis, 7 samples have been typed as AB subgroup in serology with the normal O gene, their real ABO type being CisAB in 4 cases and B(A) in 3 cases. At the same time, a kind of novel B (A)640 allele has been uncovered in this study.
Guo
Zhong-hui
ZH
Shanghai Blood Center, Shanghai Institute of Blood Transfusion, Shanghai, 200051 PR China. zhonghuiguo@hotmail.com
Xiang
Dong
D
Zhu
Zi-yan
ZY
Liu
Xi
X
Wang
Jian-lian
JL
Chen
He-ping
HP
Zhang
Jia-min
JM
Shen
Wei
W
Wang
Chen
C
Liu
Da-zhuang
DZ
D000017:ABO Blood-Group System / Q000235:genetics*; D044466:Asian People / Q000235:genetics; D001788:Blood Grouping and Crossmatching; D002681:China; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D009154:Mutation; D016133:Polymerase Chain Reaction; D012150:Polymorphism, Restriction Fragment Length
D000017:ABO Blood-Group System