Populations from Indian Himalayan and adjoining regions share their associated lactase persistence variants with the Tibetans and South Asians

The geographic distribution of lactase persistence (LP) within the global population demonstrates considerable variability. LP is linked to multiple independent mutations in a 100 bp enhancer region located 14 kb upstream of the Lactase ( LCT ) gene. Among these mutations, the -13910C>T variant was found to be identical by descent in both Europeans and Indians. Notably, the Indian Himalayan and adjoining populations (HAAPs) possess distinct genetic characteristics and share a significant proportion of ancestry with Tibetans. Previous studies identified the -13838G>A variant as the primary determinant of LP in Tibetans. In light of this, we investigated the spectrum of LP-associated variants within the HAAPs, who also have a long-standing tradition of cattle herding. Our examination of the 100 bp enhancer region of the 13th intron of MCM6 , situated 14 kb upstream of the LCT gene, among 19 HAAPs revealed one known variant (-13910C>T) and three variants, reported for the first time in Indian populations; -13838G>A, -13906T>A, and -13908C > T. We observed that both -13838G>A and -13910C>T variants in HAAPs occurred at considerable proportions, compared with other mainland Indian populations, which largely possess the -13910C>T. This further testifies that leveraging multiple populations across time helps us to understand the spread and prevalence of LP worldwide.