Molecular basis of Bombay phenotype in Mashhad, Iran: identification of a novel FUT1 deletion

A Pedigree Investigation of H-antigen Deletion Caused by Mutation of 658 C to T in the FUT1 Gene

H-antigen deletion is often caused by FUT1 gene mutation, which is a very rare blood group. In this case, the H-antigen phenotype, FUT1, FUT2 sequences, and family genetic investigation of a 26-year-old patient (proband) and her three family members were studied. The results showed that the proband and little her brother were H-deficient phenotype, their ABO genotype of both was A/O1, her father was A/B, and her mother was O1/O1. The proband and her little brother's FUT1 phenotype were both h3|h3, with a homozygous mutation 658C > T in their FUT1 gene, and the FUT1 phenotype of their parents' were H|h3, with a heterozygous mutation (658C > T) in their FUT1 gene. The result of whole gene sequencing showed that the father of the proband had a deletion of CHR19.49,255,178-49,257,177 in the FUT1 gene (hg19 was used as the reference). The results of the family investigation showed that the mutation of site 658 in the FUT1 gene between offspring and parents was consistent with Mendelian inheritance law.

Prevalence of adsorbed A antigen onto donor-derived group O red cells in children following stem cell transplantation: A single-centre evaluation

BACKGROUND AND OBJECTIVES

A group AB D-positive child presented 1 year after haematopoietic stem cell transplant (HSCT) from a group O D-negative donor as group A D-negative. Engraftment remained at 100% in white cell lineages. The reason for the unusual result was explored, and the scarcely reported phenomenon of adsorption of secreted antigen was considered. This study also investigated the prevalence of secreted antigen adsorbed onto donor-derived group O red blood cells (RBCs) in children after HSCT and defined a process for laboratory management.

MATERIALS AND METHODS

Retrospective data analysis of HSCTs carried out over 19 months at Great Ormond Street Hospital was conducted to identify cases of adsorbed A antigen after HSCT. Investigation of RBC reactions with different clones of anti-A and in vitro experiments was performed to recreate adsorption.

RESULTS

Nineteen A to O HSCTs were conducted over 19 months, of which six (31%) displayed weak A antigen on RBCs despite full myeloid engraftment. Negative reactions with anti-A were obtained when run on an alternative clone. Laboratory protocols for the future management of these cases have been developed.

CONCLUSION

Passive adsorption of secreted antigen is responsible for these results and is more widespread than previously reported, as a third of A to O HSCTs at our centre demonstrated this phenomenon. A process has been implemented into the laboratory to manage this cohort, ensuring component groups compatible with both donor and recipient are given, and the shared care centres are aware of these requirements.

Identification of two novel FUT1 mutations in people with Bombay phenotype from Iran

BACKGROUND AND PURPOSE

Bombay and Para-Bombay phenotypes are characterized by FUT1 gene mutation and lack of H antigen expression in red blood cells. ABH antigens are not present in the body secretions of Bombay individuals, while they are expressed in the secretions of para-Bombay. The aim of this study was to investigate the molecular basis of FUT1 and FUT2 genes in Iranians with the Bombay or Para-Bombay phenotype.

MATERIALS AND METHODS

ABO phenotype analysis and routine serological tests were performed on 11 people with Bombay and Para-Bombay phenotypes. The coding regions of FUT1 and FUT2 genes were amplified by PCR followed by sequencing. The ABO genotypes were also determined by sequencing exons 6 and 7 of the ABO gene.

RESULTS

Serological investigations confirmed the Bombay phenotype in 8 samples and the Para-Bombay phenotype in 3 samples. Family members with the Bombay phenotype had the classic c 0.725 T > G mutation in the FUT1 gene, accompanied by deletion of the FUT2 gene. Other samples had c.653 A>G, c 0.661 C>T, c 0.652 C>G, and c.722 A>C mutations in the FUT1 while FUT2 was silenced by c 0.461 G>A.

CONCLUSION

In this research, we identified two novel mutations in the FUT1 gene in individuals with the Bombay phenotype. This and previous works confirm the variety of FUT1 mutations.

The First Case of Para-Bombay Blood Type Encountered in a Korean Tertiary Hospital

Para-Bombay phenotypes are rare blood groups that have inherent defects in producing H antigens associated with FUT1 and/or FUT2. We report the first case of para-Bombay blood type in a Southeast Asian patient admitted at a tertiary hospital in Korea. A 23-year-old Indonesian man presented to the hospital with fever and was diagnosed with a disseminated nontuberculous mycobacterium infection and anemia. During blood group typing for blood transfusion, cell typing showed no agglutination with both anti-A and anti-B reagents. Serum typing showed strong reactivity against B cells and trace agglutination pattern with A1 cells. His red blood cells failed to react with anti-H reagents. Direct sequencing of FUT1 and FUT2 revealed a missense variation, c.328G>A (p.Ala110Thr, rs56342683, FUT1*01W.02), and a synonymous variant, c.390C>T (p.Asn130=, rs281377, Se357), respectively. This highlights the need for both forward and reverse grouping.

Mutational Analysis of Bombay Phenotype in Iranian People: Identification of a Novel FUT1 Allele

Bombay phenotype is characterized by lack of ABH antigens on RBCs and in body secretions as a result of mutations in fucosyltransferase 1 (FUT1) and fucosyltransferase 2 (FUT2) genes. The aim of this study was a mutational analysis in Iranians with this phenotype. Serological analyses including ABH and adsorption-elution tests were performed in five unrelated Bombay individuals. ABO genotyping was determined by direct sequencing. The coding regions of FUT1 and FUT2 genes were amplified and sequenced directly or after cloning into suitable vector. A novel missense FUT1 allele was detected (G1051T; G351C). Also four reported FUT1 alleles were revealed. Molecular analysis of FUT2 gene confirmed nonsecretor status in all individuals. This and our previous findings suggest the diversity and population specificity of FUT1 alleles.

The First Comprehensive Study of H-Deficient Phenotypes in Iran

Background

The lack of correct blood grouping practices can lead to missing of the rare Bombay Oh phenotype and subjecting patients to the risk of severe hemolytic transfusion reaction. In the absence of blood donor registry, transfusion management of patients is a challenge. We performed this study in order to estimate the prevalence of the Bombay blood group (Oh) in Iran and to determine whether consanguinity plays a role in the prevalence of Oh group.

Methods

This is a descriptive study in the Immunohematology Reference Laboratory of the Iranian Blood Transfusion Organization (IBTO) Tehran, Iran, over a period of 7 years. All donor blood samples showing blood group O and a strong initial reaction with blood group O RBC control cells were tested with anti-H lectin. Also blood samples from blood group O patients were tested with anti-H lectin if all cells on both antibody screening tests and antibody identification panels were reactive with negative auto control test. Specialized tests like adsorption/elution technique and inhibition assay for determination of secretor status were performed on Oh cases. Any history of consanguineous marriages were recorded. All variables were categorical variables, and percentage and proportions were calculated manually.

Results

Analysis of the results of over 7 million first-time blood donors in Iran showed that the most common ABO blood group was O, with 2,520,000 (36%) subjects. 56 Oh individuals' (donors and patients) phenotypes (0.0008%) were detected. Consanguinity was observed in 50 cases (89%).

Conclusions

This study shows that the prevalence of Bombay blood group in the general population of Iran is relatively high (0.0008%) and associated with consanguineous marriage. Thus, consanguinity is still an important risk factor present.