Six Years' Experience Performing ABO Genotyping by PCR-direct Sequencing

Won, Eun Jeong; Cho, Duck; Heo, Min Seok; Park, Hye Ryoen; Shin, Myung Geun; Ryang, Dong Wook

Abstract

BACKGROUND
ABO genotyping is essential for resolving ABO grouping discrepancy and for determinating ABO subgroups. Most clinical samples, including suspected inherited subgroups and acquired variant phenotypes, can be determined by PCR-sequencing of exons 6 and 7 in the ABO gene. Here, we describe our six years' experience performing ABO genotyping by PCR-direct sequencing.
METHODS
We conducted a retrospective investigation of serological and genotypical data from 205 samples (158 patients and 47 of their family members) of patients who were referred to the Molecular Genetics Laboratory at Chonnam National University Hwasun Hospital for ABO genotyping between January 2007 and July 2012. ABO genotyping was performed on all samples with PCR-direct sequencing of exons 6 and 7 in the ABO gene; the standard serologic tests were also performed.
RESULTS
The frequency of phenotypes consistent with their genotypes was 70.8% (112/158 cases) and the A2B3 phenotype with the cis-AB01 allele was the most common (31.0%, 49 cases) among them. The frequency of phenotypes inconsistent with their genotypes was 29.1% (46/158 cases) and the A1B3 phenotype was the most frequently recovered case (5.1%, 8 cases). Family study showed differential phenotype expression depending on the co-inherited ABO allele in five families with the B306, cis-AB01, Ael02, Aw14, or B305 allele and also showed a typical inheritance of a chimera with A102/B101/O04.
CONCLUSION
We propose that ABO genotyping using PCR-direct sequencing is useful for the resolution of ABO discrepancies and for the investigation of ABO subgroups based on six years' experience. In addition, family study for analysis of phenotypic patterns of ABO subgroups is also crucial to ABO genotyping.