Molecular diagnosis and frequencies of primary hypolactasia in populations of RUSSIA and neighboring countries

Normally, the ability to digest milk sugar (lactose) is present in every child, but not in every adult. The decrease in lactase synthesis (hypolactasia) results in the inability to digest whole milk. Recent studies of the Finnish population have associated lactase persistence in adults with allele T of the C/T−13910 polymorphism located upstream of the lactase gene; a 100% correlation of primary hypolactasia with genotype C/C has been proved. In this study, the allele and genotype frequencies of C/T−13910 were determined in populations of Russia. The frequencies of genotype C/C, varying from 36.6% in Russians to 88.2% in Chukchi, were close to the published medical and epidemiological data on the hypolactasia frequencies in these populations. Genotyping was carried out by three different methods to determine the optimal one. Genotype C/C proved to be the key determinant of primary hypolactasia. It was assumed that DNA diagnosis of genotype C/C provides a predictive test to detect primary hypolactasia long before its clinical manifestation.