A novel cis-AB allele derived from a unique 796C>A mutation in exon 7 of ABO gene

• Published in: Transfusion (Philadelphia, Pa.) Pa.), 2005-01, Vol.45 (1), p.50-55
• Main Authors: Tzeng, Cheng-Hwai, Chen, Ying-Ju, Lyou, Jau-Yi, Chen, Pei-Shan, Liu, Hsueng-Mei, Hu, Hui-Yu, Lin, Jeong-Shi, Yu, Lung-Chih
• Format: Article
• Language: English
• Subjects: ABO Blood-Group System - genetics; Alleles; Anesthesia. Intensive care medicine. Transfusions. Cell therapy and gene therapy; Biological and medical sciences; Blood and lymphatic vessels; Blood. Blood and plasma substitutes. Blood products. Blood cells. Blood typing. Plasmapheresis. Apheresis; Cardiology. Vascular system; Diseases of the peripheral vessels. Diseases of the vena cava. Miscellaneous; Exons; Female; Fundamental and applied biological sciences. Psychology; Fundamental immunology; Genetics of the immune response; Humans; Immunobiology; Medical sciences; Mutation; Transfusions. Complications. Transfusion reactions. Cell and gene therapy
• ISSN: 0041-1132; 1537-2995
• DOI: 10.1111/j.1537-2995.2005.04108.x

BACKGROUND:  The cis‐AB phenotype is very rare, and only three genotypes that correspond to specific ABO allele changes have been reported. Cis‐AB01 involves the A102 allele with a nonsynonymous substitution G803C in exon 7, whereas cis‐AB02 and cis‐AB03 involve different nonsynonymous substitutions A796C and C700T, respectively, on the B101 allele background. The nucleotide substitutions give rise to a change of the respective glycosyltransferase, resulting in varying bifunctional AB transferase activities. STUDY DESIGN AND METHODS:  Two cis‐AB phenotypes were identified in a Taiwanese C. family and two unrelated individuals, respectively. Serologic studies, molecular cloning, and sequencing of exon 6 and exon 7 were carried out to determine their respective phenotypic characteristics and cis‐AB alleles. A cohort of 300 AB‐phenotype, healthy random individuals served as controls. RESULTS:  A novel cis‐AB allele is uncovered out of the three family members, of which a 796C>A substitution occurs predicting an amino acid change at residue 266 of leucine to methionine on the background of A102 allele. It is serologically like cis‐AB03, an A2B phenotype, but molecularly different. Both of the two unrelated individuals are of cis‐AB01 allele, and all of the 300 AB blood group controls are excluded cis‐AB phenotype. CONCLUSION:  The C. family described carries a novel cis‐AB allele that differs molecularly from all previously reported cis‐AB alleles.