A Para-Bombay Blood Group Case Associated with a Novel FUT1 Mutation c.361G>A

Abstract

<b><i>Background:</i></b> Here we report a case of para-Bombay phenotype due to a novel mutation <i>FUT1</i> c.361G&#x3e;A p.(Ala121Thr) and a nonfunctional allele <i>FUT1</i>*<i>01N.13</i>(c.881_882delTT) which showed a discrepancy in the routine ABO blood group typing. <b><i>Materials and Methods:</i></b> The ABO phenotype and the Lewis blood group were typed with serological methods. The ABH antigens in saliva were determined by a hemagglutination inhibition test. The CDS region of <i>ABO, FUT1</i>and <i>FUT2</i> were amplified with polymerase chain reaction and then directly sequenced. The novel mutation was confirmed by cloning and sequencing. Three-dimensional (3-D) structural analysis of the mutant and wild-type Fut1 were performed by the Chimera software. <b><i>Results:</i></b> A, B and H antigens were not detected on the surface of red blood cells (RBCs) by the serological technique, and the B and H blood group substances were detected in the saliva, while the Lewis phenotype was Le(a–b+). Sequencing and cloning analysis showed the presence of a novel <i>FUT1</i> mutation c.361G&#x3e;A and a nonfunctional allele <i>FUT1</i>*<i>01N.13</i>(c.881_882delTT). The ABO genotype was <i>ABO</i>*<i>B.01/ABO</i>*<i>O.01.01</i>. The in silico analysis showed that the mutation p.(Ala121Thr) of <i>FUT1</i>did not change the 3-D structure of the whole enzyme but caused a certain amplitude of turnover in the loop region where Ala121 was located. <b><i>Conclusions:</i></b> A novel <i>FUT1</i> allele (<i>FUT1</i>*c.361G&#x3e;A) was identified in a Chinese individual with para-Bombay B phenotype. The <i>FUT1</i>c.361G&#x3e;A mutation may significantly downregulate the expression of H antigens on RBCs by damaging the enzyme conformation.