Prevalence of lactase persistent/non-persistent genotypes and milk consumption in a young population in north-west Russia

AIM： TO estimate the prevalence of the lactase non-persistent genotype （C/C-23910） in a northern Russian population in accordance with ethnicity, and to evaluate self-reported milk consumption depending on lactase activity. METHODS： Blood samples for genotyping lactase activity, defining the C/T-13910 variant by polymerase chain reaction, and direct sequencing were taken from 231 medical students of Russian origin aged 17-26 years. We analyzed milk product consumption by questionnaire which was specially designed for the estimation of milk consumption and abdominal complaints. RESULTS： We found that the prevalence of the C/C-13190 genotype in the northern Russian population was 35.6%. The other genotypes nearby C/T-13910 and associated with lactase activity were not present in the study population. The consumption of milk among people with the non-persistent genotype tended to be lower than among the lactose tolerant subjects, but was not statistically significant. CONCLUSION： An investigation of the lactase persistent genotype in a northern Russian population has not been performed before, The genotype did not affect the consumption of milk products in this population which could be explained by low consumption of milk products among the entire study population.

乳糖酶基因C/T-13910多态性与腰椎骨密度关系的meta分析

目的:探讨乳糖酶基因C/T-13910多态性与腰椎骨密度的关系。方法:计算机检索Web of Science、Pub Med、Embase、中国知网和万方等数据库,检索时限为建库至2021年10月1日,采用Stata 11.0软件进行meta分析。结果:纳入7篇文献,共8740例研究对象。meta分析结果显示:显性基因模型(TT/TC vs TC:WMD=0.018,95%CI=-0.002~0.037,P=0.077),超显性基因模型(TT/CC vs TC:WMD=-0.009,95%CI=-0.025~0.006,P=0.231),隐性基因模型(TT vs TC/CC:WMD=-0.002,95%CI=-0.013~0.010,P=0.778)与腰椎骨密度无显著关系。结论:乳糖酶基因C/T-13910多态性与腰椎骨密度无显著关系。

Molecularly defined adult-type hypolactasia among working age people with reference to milk consumption and gastrointestinal symptoms

AIM: To study milk consumption and subjective milk- related symptoms in adults genotyped for adult-type hypolactasia. METHODS: A total of 1900 Finnish adults were genotyped for the C/T-13910 variant of adult-type hypolactasia and filled in a structured questionnaire concerning milk consumption and gastrointestinal problems. RESULTS: The C/C-13910 genotype of adult-type hypolactasia was present in 18% of the study population. The prevalence of the C/C-13910 genotype was higher among subjects who were undergoing investigations because of abdominal symptoms (24%, P < 0.05). Those with the C/C-13910 genotype drank less milk than subjects with either the C/T-13910 or the T/T-13910 genotype of lactase persistence (18% vs 38%; 18% vs 36%, P < 0.01). Subjects with the C/C-13910 genotype had experienced more gastrointestinal symptoms (84%) during the preceding three-month period than those with the C/T-13910 (79%, P < 0.05) or the T/T-13910 genotype (78 %, P < 0.05). Only 9% (29/338) of the subjects with the C/C-13910 genotype consumed milk and reported no symptoms from it.CONCLUSION: Gastrointestinal symptoms are more common among adults with the C/C-13910 genotype of adult-type hypolactasia than in those with genotypes of lactase persistence.

Correlation of intestinal disaccharidase activities with the C/T_(-13910) variant and age

AIM： To correlate the C/T-13910 variant, associated with lactase persistence/non-persistence （adulttype hypolactasia） trait, with intestinal disaccharidase activities in different age groups of the adult population.METHODS： Intestinal biopsies were obtained from 222 adults aged 18 to 83 years undergoing upper gastrointestinal endoscopy because of unspecified abdominal complaints. The biopsies were assayed for lactase, sucrase and maltase activities and genotyped for the C/T-13910 variant using PCR-minisequencing. RESULTS： There was a significant correlation between lactase activity and the C/T-13910 variant （P 〈 0.00001）. The mean level of lactase activity among subjects with C/C-1391o genotype was 6.86± 0.35 U/g, with C/T-13910 genotype 37.8 ± 1.4 U/g, and with T/T-13910 genotype 57.6± 2.4 U/g protein, showing a trimodal distribution of this enzyme activity. Significant differences were also observed in maltase activities among individuals with different C/T-13910 genotypes （P = 0.005）. In contrast, in sucrase activity, no significant differences emerged between the C/T-13910 genotypes （P = 0.14）. There were no statistical differences in lactase （P = 0.84）, sucrase （P = 0.18）, or maltase activity （P = 0.24） among different age groups. In the majority （〉 84%） of the patients with the C/C-13910 genotype associated with lactase non- persistence, the lactase activity was less than 10 U/g protein.CONCLUSION： Our study demonstrates a statistically significant correlation between the C/T-13910 genotype and lactase activity and this correlation is not affected by age in adults but the cut-off value of 20 U/g protein used for the diagnosis of lactase non-persistence might be too high.