Two novel alleles on Fucosyltransferase 2 from northern Thai para-Bombay family and computational prediction on mutation effect.

BACKGROUND: Major characteristics of the para-Bombay phenotype are the absence of ABH antigens on red blood cells due to fucosyltransferase 1 (FUT1) gene mutation and the presence of these antigens in body secretions due to the active fucosyltransferase 2 (FUT2) gene. An ABO blood group discrepancy can be identified via serological testing, and additional tests can be performed for confirmation. This study aimed to resolve the ABO discrepancy and report two novel alleles on the FUT2 gene in northern Thai para-Bombay families. STUDY DESIGN AND METHODS: Twelve blood samples were collected from five suspected para-Bombay donors and their families. Nucleotide sequences of ABO, FUT1, and FUT2 were analyzed by polymerase chain reaction-sequence-based typing. Bioinformatics tools were used to predict the effect of suspected novel FUT2 alleles. RESULTS: All samples exhibited normal ABO alleles, concordant with serological test results. FUT1 exhibited three known variants (c.328G>A, c.424C>T, and c.658C>T). Although FUT2 exhibited two known variants (c.357C>T and c.385A>T), two novel alleles were observed. One allele consisted of c.98A>G, c.101T>G, and c.357C>T with predicted normal transferase activity, whereas the other consisted of c.357C>T and c.617T>C with predicted abnormal enzyme activity. DISCUSSION: Two novel alleles in FUT2 were reported among the affected para-Bombay individuals of northern Thai families. The c.617T>C variant caused an amino acid change from valine to alanine at position 206, predicted to be an inactive FUT2 enzyme. Inheritance of this variant with the recessive FUT1 allele may lead to inheritance of the rare Bombay blood group in the progeny.

HLA-DRB1*04:05 and HLA-DQB1*04:01: Alleles Potentially Associated with Vogt-Koyanagi-Harada in Northern Thai Patients.

PURPOSE: To determine the frequency and association of alleles at human leukocyte antigen (HLA)-DRB1 and HLA-DQB1 loci in VKH disease patients from Northern Thailand. METHODS: A case-control study was conducted with three subject groups: 23 VKH patients, 20 patients with other uveitis entities, and 40 healthy blood donors. HLA-DRB1 and HLA-DQB1 loci were analyzed and the frequency of HLA-DRB1 and HLA-DQB1 alleles was calculated by direct counting. The measure of association was calculated by odds ratio (OR) and 95% confidence interval. RESULTS: In VKH patients, the most prevalent allele was HLA-DRB1*04:05, found in 35% of patients and with the highest OR (42.13). HLA-DQB1*04:01 was the next most prevalent, found in 23.91% of VKH patients. HLA-DQB1*05:02 was also detected in 23.91% of patients; however, a higher prevalence was observed in non-VKH and healthy controls (30% and 35%, respectively). CONCLUSION: HLA-DRB1*04:05 and HLA-DQB1*04:01 could be potential genetic markers for VKH.