Abstract
Lactase non-persistence (leading to primary lactose intolerance) is a genetically dependent inability to digest lactose in adulthood. As part of the human adaptation to dairying, the human lactase LCT-13910C/T mutation (which propagates adult expression of lactase) developed, spread and participated in the adaptation to dairying. This variant is associated with lactase activity persistence, and its carriers are able to digest lactose. We compared the frequencies of lactase 13910C/T (rs4988235) genotypes in Czechs/Slavs (N = 288) and Czech Gypsies/Roma (N = 300), two ethnically different groups where this polymorphism has not yet been analysed. Allelic frequencies significantly differed between the populations (p < 0.0001). In Czechs/Slavs, the lactase persistence T allele was present in 76% of the individuals, which is in agreement with frequencies among geographically neighbouring populations. In the Czech Gypsy/Roma population, only 27% of the adults were carriers of at least one lactase persistence allele, similar to the Indian population. In agreement with this result, dairy product consumption was reported by 70.5% of Czechs/Slavs and 39.0% of the Czech Gypsy/Roma population. Both in the Czech Gypsy/Roma and in the Czech/Slavs populations, the presence of carriers of the lactase persistence allele was similar in subjects self-reporting the consumption of unfermented/fresh milk, in comparison to the others.
Highlights
Lactase is an enzyme that cleaves disaccharide lactose into two simple sugars, glucose and galactose, both of which, unlike lactose, can be absorbed
Lactase non-persistence leads to primary lactose intolerance and usually occurs between early childhood and puberty
Lactase is coded by the LCT gene (OMIM acc No 603202)
Summary
Lactase (lactase-phlorizin hydrolase–enzyme activities as described in EC 3.2.1.23 and EC 3.2.1.62) is an enzyme that cleaves disaccharide lactose (obtained in milk at about 4%) into two simple sugars, glucose and galactose, both of which, unlike lactose, can be absorbed. Lactase persistence mutations are not evenly distributed across ethnic groups (Mattar et al, 2012; Gerbault et al, 2013), but they appear to reflect the ancient history of dairying among populations and of migration events. In Europeans, the C ® T exchange at position -13,910 on the LCT gene (rs4988235) is the most common (Mattar et al, 2012) lactase persistence variant and has been confirmed to be functional in vivo (Fang et al, 2012).
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