A novel FUT1*c.889C>T allele associated with the para-Bombay AB phenotype and computational evaluation of the mutation effect

Background: Mutation in the FUT1 gene can impact the structure and function of α-(1,2)-fucosyltransferase 1 (α2FucT1). To explain the para-Bombay phenotype of a novel FUT1 allele, three-dimensional (3D) modeling and mutation effect analysis of α2FucT1 were performed by bioinformatic tools.

Materials and methods: Blood and saliva samples were collected from a patient who was suspected to be a para-Bombay phenotype. H, A, and B antigens were determined with routine serologic methods for those samples. FUT1 and FUT2 coding regions were determined by Sanger sequencing. The novel heterozygous mutation was confirmed by cloning and sequencing. 3D model of mutant α2FucT1 was built by Phyre 2 and the mutation effect was evaluated by Chimera, PROVEAN, and Polyphen-2.

Results: Weak H, A, and B antigens were detected on RBCs of the proband and normal quantities of H, A, and B antigens were observed in his saliva. Cloning sequencing showed that the proband carried a novel FUT1 allele (c.889C>T, p.Leu297Phe) and a null FUT1*01N.06 allele. 3D model showed that the p.Leu297Phe variant in α2FucT1 reduced the number of hydrogen bonds and the mutation effect was predicted to be deleterious and possibly damaging, which suggested that the conformation and activity of the enzyme might be significantly damaged.

Conclusion: A novel missense mutation led to an amino acid variant p.Leu297Phe in α2FucT1, which was a potential cause of the inactivation of the enzyme. Computational evaluation was a convenient and useful approach for the mutation effect analysis of the enzyme.