A study on genetic test of lactase persistence in relation to milk consumption in regional groups of India

Lactase nonpersistence (LNP) is characterized by the decrease in lactase expression in the small intestine. Studies have shown that -13910 C>T and -22018 G>A single-nucleotide polymorphisms (SNPs) located upstream of the lactase gene are associated with an LNP/lactase persistence (LP) trait. The current study evaluated the LP allelic frequency in 227 healthy Indian subjects consisting of North Indians, Maharashtrians, Gujaratis, Parsis, and South Indians, and for the first time assessed its relation with milk consumption pattern in Indian subjects. The two SNPs were genotyped using the polymerase chain reaction and restriction fragment length polymorphism methods. The milk consumption pattern for the studied subjects was noted by questionnaire. The two SNPs were present in a strong linkage disequilibrium. LP prevalence varied in these Indian regional groups. The LP frequency was highest for North Indians and lowest for Parsis (p=0.03 CC vs. CT+TT, p=0.008 GG vs. GA+AA). South Indians had a lower LP frequency compared to North Indians (p=0.07 for each SNP). The milk consumption pattern varied in these Indian subgroups, with the Gujaratis exhibiting the highest milk intake and Parsis the lowest (p=0.04). Our study indicates that the milk intake in Indians might be influenced by their dietary habits in addition to their ancestral history. An overall correlation, however, between milk consumption and LP genotypes was not observed.