Distribution of MN blood group types in local populations in Philippines

Abstract

The classification of MN system of human blood type is based on the presence of either glycophorin A (GPA) or glycophorin B (GPB) in the erythrocyte membrane, leading to the expression of the M or N antigen for GPA and only the N antigen for GPB (Kudo and Fukuda 1994). The MN system has been known to indicate specific kinds of immune responsiveness as well as serve as viable genetic markers for particular health conditions and diseases (Delanghe et al. 1995). The mode of inheritance of the agglutinogens M and N is through a single set of allelomorphic alleles wherein the M and N alleles are codominant to each other. This allows the heterozygote MN to have a distinguishable phenotype from the homozygous MM and NN (Mourant et al. 1976). The codominant nature of the M and N alleles makes it convenient to test whether a population exhibits Hardy– Weinberg equilibrium (HWE) at the MN blood group locus. MN blood groups have shown to exhibit differences in allele frequency in different populations, but are typically in HWE (Furuhata et al. 1954; Morton and Chung 1959; Lee 1965; Breguet et al. 1986). Thus, genetic drift is a likely reason for the differences in the frequencies of the M and N alleles between human populations. Despite the significance of the MN blood groups in the fields of genetics and health, only two prior published data sets on the MN blood group in Philippines are available; one study was restricted to Manila (Fraser et al. 1964), while the other compared the frequency distribution ofM and N alleles between a population based in Manila and another in a rural town of Northern Luzon (Guzman et al. 2009). Through surveying of the MN blood types, the present study aimed to (i) produce the first comprehensive pool of data on the distribution of the MN blood groups in Philippines; (ii) determine the frequencies of theM and N alleles in various populations from the major Philippine island groups of Luzon, Visayas, Mindanao and Palawan; and (iii) test whether or not these populations are at HWE.