The influence of Scandinavian presence on Greenlandic lactase persistence

Background: The study aims to estimate the prevalence of lactase non-persistence (LNP) among Greenlandic Inuit and Scandinavians living in Nuuk and East Greenland. The C to T transition in LCT - 13910 (rs4988235) is an autosomal inherited variant that provides the ability to lifelong lactase production, necessary to digest milk. The transition is very common in North European populations. However, LNP has only been sparsely studied in Greenland and never in Eastern Greenland, and genotype data has not previously been reported.Methods: Whole blood samples were collected from 535 participants, and rs4988235 was typed using a PCR-based method. Ethnicity was defined by parents' place of birth. Results were compared between East and West Greenland and Inuit and Scandinavians using Pearson's Chi2 test.Results: 82.2% of the participants were Inuit, and 17.8% were of Scandinavian ancestry. Among Inuit, 88.5% had LNP compared to 7.5% among Scandinavians (p < 0.001). The prevalence of LNP in Inuit varied significantly between East and West Greenland (p < 0.001). In the capital, 67.6% of Inuit had LNP compared to 98.6% in Tasiilaq and 100% in the villages around Tasiilaq.Discussion: The difference in LNP between East and West Greenland and the Inuit and Scandinavian population found in our study suggests that the original Inuit population was lactose maldigesters. Our findings suggest that the -13910 T allele was introduced into the original Inuit population by the Danes.