The M142T mutation causes B3 phenotype: three cases and an in vitro expression study.
The B3 phenotype is the most common B subtype in Korea. The B305 allele (425 T>C, M142T) was first reported in 2 Chinese individuals; however, it has not yet been reported in the Koreans, and the impact of the M142T mutation on the expression of the B3 phenotype has also not been studied. To resolve an ABO discrepancy between a group O neonate and her group O father and A(1)B(3) mother, blood samples from these individuals and other family members were referred to our laboratory for ABO gene analysis. The B305 allele was discovered in the neonate (B305/O01), her mother (A102/ B305), and her maternal aunt (B305/O02), while her father was typed as O01/O02. Transient transfection experiments were performed in HeLa cells using the B305 allele synthesized by site-directed mutagenesis; flow cytometric analysis revealed that this transfect expressed 35.5% of the total B antigen produced by the B101 allele transfect. For comparison, Bx01 allele transfects were also created, and they expressed 11.4% of the total B antigen expressed on the surface of B101 transfects. These experiments demonstrate that the M142T (425 T>C) mutation is responsible for the B subtype phenotype produced by the B305 allele.
Cho
Duck
D
Department of Laboratory Medicine1, Chonnam National University Medical School, Gwangju, Korea. dcho@chonnam.ac.kr
Shin
Dong-Jun
DJ
Yazer
Mark Harris
MH
Ihm
Chun-Hwa
CH
Hur
Young-Moon
YM
Kee
Seung-Jung
SJ
Kim
Soo-Hyun
SH
Shin
Myung-Geun
MG
Shin
Jong-Hee
JH
Suh
Soon-Pal
SP
Ryang
Dong-Wook
DW
D000017:ABO Blood-Group System / Q000235:genetics*; D000328:Adult; D000483:Alleles; D019943:Amino Acid Substitution; D002648:Child; D005260:Female; D005434:Flow Cytometry; D005786:Gene Expression Regulation; D005838:Genotype; D006367:HeLa Cells; D006801:Humans; D009154:Mutation; D010641:Phenotype; D020641:Polymorphism, Single Nucleotide; D017422:Sequence Analysis, DNA; D014162:Transfection
D000017:ABO Blood-Group System