The -13914G>A variant upstream of the lactase gene (LCT) is associated with lactase persistence/non-persistence

• Published in: Scandinavian journal of clinical and laboratory investigation Vol. 70; no. 5; pp. 354 - 357
• Main Authors: Khabarova, Yulia, Torniainen, Suvi, Savilahti, Erkki, Isokoski, Mauri, Mattila, Kari, Järvelä, Irma
• Format: Journal Article
• Language: English
• Published: England Informa Healthcare 01.09.2010; Taylor & Francis
• Subjects: Disaccharidase activity; Disaccharidases - genetics; family study; Female; genotype; Humans; hypolactasia; Lactase - genetics; lactose intolerance; Lactose Intolerance - genetics; Middle Aged; Pedigree; Polymorphism, Single Nucleotide; Russia; Russia
• ISSN: 0036-5513; 1502-7686
• DOI: 10.3109/00365513.2010.491554

Abstract Background. Adult-type hypolactasia (lactase non-persistence) is a common cause of gastrointestinal symptoms. Several DNA sequence variants have been identified for the lactase-persistence/non-persistence (LP/LNP), the most common being the C to T residing -13910 bp upstream of the lactase gene (LCT). We have analysed sequence variants of LP/LNP in subjects originating from Northern Russia. Methods. A total of 148 subjects with gastrointestinal complaints were genotyped covering about 400 bp around the -13910C/T variant using direct PCR-sequencing. All patients were interviewed about milk-related symptoms using the questionnaire. Disaccharidase activities were measured from intestinal biopsy specimens of the index person. Results. The prevalence of the -13910C/C genotype among 148 patients was 28.4%. A G to A variant residing 13914 bp upstream from the LCT gene (-13914G>A) was identified in one participant carrying the -13910C/C genotype. In two biopsy specimens her lactase activity was above the generally accepted cut off level for adult-type hypolactasia, 10U/g protein. Three other family members also carried the -13914G>A genotype. Among eight family members five had the LNP genotype -13910C/C. Conclusion. A rare variant G to A residing 13914 bp upstream of the LCT gene was identified in a subject carrying the more frequent variant -13910C/C. The -13914G>A variant in heterozygous state was associated with increased lactase activity, suggesting that the increased lactase activity is most likely to be associated with the -13914G>A variant. Further studies need to be done to confirm the functional role of this variant.