Two new FUT2 (fucosyltransferase 2 gene) missense polymorphisms, 739G → A and 839T → C, are partly responsible for non-secretor status in a Caucasian population from Northern Portugal

Abstract

Secretor status is defined by the expression of H type 1 antigen on gastric surface epithelium and external secretions. The H type 1 structure, and other fucosylated carbohydrates (Lea, sialyl-Lea, Le b, Lex, sialyl-Lex and Ley), can serve as ligands for several pathogens, including Helicobacter pylori, and are cancer-associated antigens. Secretor individuals are more susceptible to some bacterial and viral infections of the genito-urinary and digestive tracts. The aim of the present study was to examine FUT2 (fucosyltransferase 2 gene) polymorphisms in a Caucasian population of non-secretor individuals (M = 36) from northern Portugal and to evaluate the activity of the mutant FUT2 enzymes. The secretor status was determined by UEAI [Ulex europaeus (gorse) lectin] histochemistry in gastric mucosa, and FUT2 polymorphisms were studied by restriction-fragment-length polymorphism and direct sequencing. The majority of non-secretors (88.9%) were homozygous for 428G → A polymorphism; 5.6% were homozygous for 571C → T and 5.6% were homozygous for two new missense polymorphisms, 739G → A (2.8%) and 839T → C (2.8%). By kinetic studies it was demonstrated that the two new FUT2 mutants (739G → A and 839T → C) are almost inactive and are responsible for some non-secretor cases.