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A novel A allele with 664G>A mutation identified in a family with the A m phenotype
Author(s) -
Lin Marie,
Hou MinJu,
Twu YuhChing,
Yu LungChih
Publication year - 2005
Publication title -
transfusion
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.045
H-Index - 132
eISSN - 1537-2995
pISSN - 0041-1132
DOI - 10.1111/j.1537-2995.2005.04132.x
Subject(s) - transferase , phenotype , allele , mutation , microbiology and biotechnology , abo blood group system , gene , genetics , biology , exon , enzyme , biochemistry
BACKGROUND: The A m phenotype has been characterized as a weak expression of the A antigen on red blood cells but the presence of a normal quantity of the A antigen in saliva. This study describes a molecular genetic analysis of members of an A m family. STUDY DESIGN AND METHODS: The eight exon regions of the ABO genes of the A m proposita were amplified by polymerase chain reaction and cloned, and their sequences were analyzed. The α‐1,3‐ N ‐acetylgalactosaminyltransferase (A‐transferase) activities of the A m serum and the expressed A m transferase were analyzed. RESULTS: An A gene with a 664G>A mutation, which predicts an amino acid alteration of Val222Met, was identified in the A m proposita. This A m 664A allele was demonstrated in other three family members with the A m phenotype. The A‐transferase activity was virtually undetectable in the A m sera, and the expressed A m transferase showed weak A‐transferase activity, when compared with the expressed A 1 transferase, in assays that use acceptor substrates mimicking the Type 2 H structure and Type 1 H structure. CONCLUSION: A novel A allele with 664G>A mutation was demonstrated in a pedigree with the A m phenotype. The mechanism leading to the formation of the A m phenotype still awaits elucidation.