Identification of a novel nonsense mutation (c.618C>G, p.Tyr206Ter) in the ABO gene in a Chinese individual

The ABO gene is mainly composed of A, B, and O alleles. The most common O alleles share one nucleotide deletion of G at position 261 in the ABO gene. This report found a novel nonsense mutation in an ABO allele which led to group O in a Chinese individual. Forward and reverse typing tests were carried out first using the manual tube method. Weak expression of A or B antigens on red blood cells (RBCs) was confirmed by absorption and elution test. Exons 6 and 7 in the ABO gene were amplified and direct-sequenced. The haplotypes of the ABO gene were identified by clone-sequencing. Serologic results showed that the phenotype of proband was group O. Based on direct sequencing results, the proband was heterozygous for the ABO*A1.01 allele and ABO*O.01.01 allele, except for a heterozygous c.618C>G mutation. The clone sequencing demonstrated that a nonsense C>G mutation at position 618 was identified in exon 7 of the ABO*A1.01-like allele, which caused a p.Tyr206Ter exchange in the ABO glycosyltransferase. Thus, the novel ABO allele was classified as O allele. The study suggested that a novel nonsense mutation in the ABO gene was identified in a Chinese individual with group O, resulting in the truncated, 205-amino-acid ABO glycosyltransferase, which lost its transferase activity.