Department of Experimental Medicine and Biotechnology, Postgraduate Institute of Medical Education and Research, Chandigarh, 160012, India.
Genes Nutr. 2013 Jan;8(1):145-51. doi: 10.1007/s12263-012-0305-7. Epub 2012 Jul 5.
Adult-type hypolactasia (AtH or lactase non-persistence) is the physiological decline in lactase activity that manifests in majority of the world's population after weaning. Recently, various single-nucleotide polymorphisms (SNPs) upstream of lactase gene (LCT) have been suggested to be associated with AtH or the lactase persistent trait in different human populations. C/T -13910 SNP was found be completely associated with AtH in Finnish population, and G/A -22018 SNP was found to be strongly, but not completely, associated with AtH. The aim of this study was to correlate G/A -22018 SNP with intestinal lactase activity in North Indian children. These children were also genotyped for C/T -13910 SNP. We also examined the differences in milk consumption and milk-related clinical symptoms in children with different genotypes of G/A -22018 and C/T -13910 SNPs. Intestinal biopsies were obtained from 231 children aged 2-16 years undergoing routine endoscopy for various abdominal complaints. The biopsies were assayed for lactase, sucrase, and maltase activities and genotyped for G/A -22018 and C/T -13910 SNPs using restriction fragment length polymorphism and DNA sequencing analysis. There was a significant correlation between lactase activity and different genotypes of G/A -22018 SNP. Children with G/G -22018 genotype had low lactase activity. With a reference value of <10 U/g protein (lactase activity) to be indicative of AtH, the sensitivity and specificity of genetic test based on G/A -22018 SNP was 94.4 and 94.1 %, respectively. Furthermore, the consumption of milk was lower in children with G/G -22018 genotype. Flatulence was the only symptom significantly more frequent among the children with G/G -22018 genotype compared to those with G/A and A/A -22018 genotypes. However, most of the children with G/G -22018 genotype seem to tolerate small amounts of milk without any significant difference in gastrointestinal symptoms from those with G/A and A/A -22018 genotypes.
成人型乳糖酶缺乏症（AtH 或乳糖酶持续性）是指断奶后世界上大多数人口中乳糖酶活性的生理性下降。最近，各种乳糖酶基因（LCT）上游的单核苷酸多态性（SNP）被认为与不同人群中的 AtH 或乳糖酶持续性特征有关。在芬兰人群中，发现 C/T-13910 SNP 与 AtH 完全相关，而 G/A-22018 SNP 则与 AtH 强相关，但不完全相关。本研究的目的是在北印度儿童中，将 G/A-22018 SNP 与肠道乳糖酶活性相关联。这些儿童还进行了 C/T-13910 SNP 的基因分型。我们还检查了不同 G/A-22018 和 C/T-13910 SNP 基因型儿童的牛奶摄入量和与牛奶相关的临床症状的差异。从 231 名 2-16 岁因各种腹部不适而接受常规内镜检查的儿童中获得肠活检。使用限制性片段长度多态性和 DNA 测序分析，对活检进行乳糖酶、蔗糖酶和麦芽糖酶活性检测，并对 G/A-22018 和 C/T-13910 SNP 进行基因分型。乳糖酶活性与 G/A-22018 SNP 的不同基因型之间存在显著相关性。G/G-22018 基因型的儿童乳糖酶活性低。以<10U/g 蛋白（乳糖酶活性）为参考值，基于 G/A-22018 SNP 的遗传检测的敏感性和特异性分别为 94.4%和 94.1%。此外，G/G-22018 基因型儿童的牛奶摄入量较低。与 G/A 和 A/A-22018 基因型的儿童相比，G/G-22018 基因型的儿童只有腹胀症状更为频繁。然而，大多数 G/G-22018 基因型的儿童似乎可以耐受少量的牛奶，与 G/A 和 A/A-22018 基因型的儿童相比，胃肠道症状没有明显差异。
