Evaluation of a Genetic Test for Diagnose of Primary Hypolactasia in Northeast of Iran (Khorasan)

Document Type: Original Article

Authors

1 Departmant of Human Genetic, Mashhad University of Medical Sciences, Mashhad, Iran

2 Iranian Academic Centres for Education, Culture and Research (ACECR)

Abstract

Objective(s) Primary or adult type hypolactasia, the most common enzyme deficiency in the world, is due to reduced lactase activity in the intestinal cell after weaning. Lactase non-persistence is inherited as an autosomal recessive trait. A DNA variant, single nucleotide polymorphism C/T−13910 which is located on 13910 base pairs (bp) upstream of the lactase gene (LCT) at chromosome 2 has been show to associate with the lactase persistence/non-persistence. The prevalence of the C/T-13910 variant is different for hypolactasia in European, Asian, African-American and Northern African populations. In this study, we investigated, for the first time the allele frequent of the single nucleotide polymorphism C/T−13910 in the Iranian population in khorasan province with hypolactasia. Materials and Methods Peripheral blood was collected from 100 subjecs with primary hypolactasia and 100 healthy individuals as a control group. Genomic DNA was extracted. The genotype was analyzed with the PCR-RFLP method. A statistical analysis was performed by chi-square test using SPSS software. A P-value of <0.05 was considered statistically significant.
Results
In case group allelic frequency for SNP T-13910C (C, T) was respectively 95%, 5% vs. control group 86% and 14%. Genotype frequency (CC, CT, TT) in patient group was 90%, 10%, 0% vs. control group 74%, 24% and 2%. So according to our findings, there were significant differences between allelic frequencies (P=0.03), and in genotype frequency between case and control groups (P=0.006).
Conclusion
Based on our results, analysis of C\T-13910 polymorphism can be used as a simple genetic test for diagnosis of primary type hypolactasia in the Iranian population.

Keywords


1. Kaur K, Mahmood S, Mahmood A. Hypolactasia as a molecular basis of lactose intolerance. IJBB 2006; 43:267-274.
2. Lomer MCE, Parkes GC, Sanderson JD, Intolerance L. High frequency of MCM6 lactose intolerance genotype in Polynesian People. AP& T 2010. 32: 829–830.
3. Swagerty DL, Walling AD, Klein RM. Lactose intolerance. Am Fam Physician 2002; 65:1845-1860.
4. Mattar R, Monteiro MS, Silva JMK, Carrilho FJ. LCT-22018G> A single nucleotide polymorphism is a better predictor of adult-type hypolactasia/lactase persistence in Japanese-Brazilians than LCT-13910C> T. Clin 2010; 65:1399–1400.
5. Rasinpere H, Savilahti E, Enattah NS, Kuokkanen M, Tِtterman N, Lindahl H, et al A genetic test which can be used to diagnose adult-type hypolactasia in children. Gut 2004; 53:1571-1576.
6. Büning C, Genschel J, Jurga J, Fiedler T, Voderholzer W, Fiedler EM, et al Introducing genetic testing for adult-type hypolactasia. Digestion 2005; 71:245-250.
7. Weiskirchen R, Tag CG, Mengsteab S, Gressner AM, Ingram CJE, Swallow DM. Pitfalls in LightCycler diagnosis of the single-nucleotide polymorphism 13.9 kb upstream of the lactase gene that is associated with adult-type hypolactasia. Clin Chim Acta 2007; 384:93-98.
8. Anthoni SR, Rasinpera HA, Kotamies AJ, Komu HA, Pihlajamak HK, Kolho KL, et al Molecularly defined adult-type hypolactasia among working age people with reference to milk consumption and gastrointestinal symptoms. World J Gastrointest Endosc 2007; 13:1230-1235.
9. Kruse TA, Bolund L, Grzeschik KH, Ropers HH, Sjoestroem H, Noren O, et al The human lactase-phlorizin hydrolase gene is located on chromosome 2. FEBS lett 1988; 240:123-126.
10. Sahi T, Isokoski M, Jussila J, Launiala K, Pyorala K. Recessive inheritance of adult-type lactose malabsorption. Lancet 1973; 302:823-826.
11. Enattah NS, Sahi T, Savilahti E, Terwilliger JD, Peltonen L, Jaevelae. Identification of a variant associated with adult-type hypolactasia. Nat Genet 2002; 30:233-237.
12. Troelsen JT, Olsen J, Moeller J, Sjoestroem H. An upstream polymorphism associated with lactase persistence has increased enhancer activity. Gastroenterology 2003; 125:1686-1694.
13. Kuokkanen M, Enattah NS, Oksanen A, Savilahti E, Orpana A, Jaevelae. I. Transcriptional regulation of the lactase-phlorizin hydrolase gene by polymorphisms associated with adult-type hypolactasia. Gut 2003; 52:647-652.
14. Tishkoff SA, Reed FA, Ranciaro A, Voight BF, Babbitt CC, Silverman JS, et al Convergent adaptation of human lactase persistence in Africa and Europe. Nat Genet 2006; 39:31-40.
15. Sadre M, Karbasi K. Lactose intolerance in Iran. Am J Clin Nutr 1979; 32:1948-1954.
16. Rahgozar S, Salehi Mansour PEAA, Moafi AR, Jarvela I, Fatehifar MR. Study of c/t-13910 variant in association with primary hypolactasia (ph) in the rural population of central Iran. Hakim 2004; 7:55-60.