[Studies on distribution of H type 1-H type 4 antigens of ABO system and on FUT2 polymorphism]

I have examined the immunohistochemical distribution of H type 1-H type 4 antigens of the ABO system in human submandibular gland using either of the three anti-H monoclonal antibodies specific for H type 1, H type 2 and H type 3/4. I have clearly identified cell types expressing H type 1, H type 2 and H type 3/4: H type 1 in mucous cells and duct cells, H type 2 in duct cells, and H type 3/4 in serous cells of the submandibular gland. The expression of H type 1 and H type 3/4 in the human submandibular gland is regulated by the Se enzyme. The FUT2 encodes Secretor type alpha(1,2) fucosyltransferase (Se enzyme), which regulates the expression of ABH antigens in the gastrointestinal tract and secretions. Molecular analysis of the FUT2 polymorphism of various populations have indicated the ethnic specificity of null alleles: the null allele se428 is a common Se-enzyme deficient allele in Africans and Caucasians but does not occur in Asians, whereas the null allele se357,385 is specific to Asians. The gene frequency of se428 or se357,385 is about 0.5 in each respective population. Why the se428 is absent in Asians is of interest.