A Novel A^el Allele Derived from a Unique 816insG in Exon 7 of the ABO Gene

The ABO blood group system is the most important blood group system in transfusion medicine. In addition to the major A, B and O alleles, many rare alleles with weak expression of the A or B antigens on RBCs have been defined. We report here the molecular analysis of a novel A^el allele. Exons 6 and 7 of the ABO gene were PCR-amplified, cloned and sequenced for the propositus, Mr C, who is a 56-year-old Taiwanese male and was incidentally observed to have an A_el phenotype. His direct family members including wife, son and daughter were subsequently enrolled for further study. Three hundred random blood donors of AB phenotype served as control. A novel A^el allele was uncovered from the propositus and his daughter, of which a unique 816insG mutation occurred on the A102 background that results in a frame shift leading to a 37-amino acid longer polypeptide than the normal A1 transferase, a finding similar to that of Ael01 allele with 804insG. We found that the C family carried a novel A^el allele that differs molecularly from seven A^el alleles reported in the literature.

Key Words:  ABO gene , molecular genetic analysis , novel A^el allele

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