1. Lactase persistence/non-persistence variants, C/T_13910 and G/A_22018, as a diagnostic tool for lactose intolerance in IBS patients.
- Author
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Bernardes-Silva, Carlos Felipe, Pereira, Alexandre C., de Fátima Alves da Mota, Glória, Krieger, José Eduardo, and Laudanna, Antonio Atílio
- Subjects
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LACTOSE intolerance , *CARBOHYDRATE intolerance , *GENETIC polymorphisms , *CHROMATOGRAPHIC analysis - Abstract
Abstract: Background: Irritable bowel syndrome (IBS) is a symptom-based disorder characterized by abdominal pain related to altered bowel habit. We evaluated the predictive power of 2 genetic markers of hypolactasia, C/T_13910 and G/A_22018, in IBS patients with and without lactose intolerance in order to gain insight into the role of lactose intolerance in IBS. Methods: Seventy five patients (59F/16M, mean age: 49.6±14.2 years) with an IBS diagnosis based on Rome II criteria and 272 healthy individuals, where 74 (58F/16M, 54.1±10.9 years) were matched-controls, were evaluated. IBS and healthy individuals were genotyped for the C/T_13910 and G/A_22018 polymorphisms nearby the lactase-phlorizin hydrolase gene. Hydrogen breath test (HBT) with gas chromatography was performed in IBS patients to assess for lactose intolerance. Results: Of the 75 IBS patients, 28 (37%) were defined as lactose intolerants. The grade/severity of symptoms after an oral lactose load were positively correlated to the expiratory H2 excretion (P <0.001). Alleles and genotypes frequencies from C/T_13910 and G/A_22018 were not significantly different between IBS patients and control individuals (P >0.05;NS). Presence of the C and G allele were positively associated with a higher expiratory hydrogen excretion and more intense gastrointestinal symptoms (P <0.001). Considering these polymorphisms as a diagnostic test for lactose intolerance in IBS patients, presence of the CC and GG genotypes were estimated to have, a sensitivity of 100% and 96%, respectively; and a specificity of 83% and 79%, positive predictive value of 76% and 73%, and negative predictive value of 100% and 97%. Conclusions: In IBS patients, genotyping of C/T_13910 and G/A_22018 polymorphisms predicts gastrointestinal symptoms after lactose ingestion and are a diagnostic tool for lactose intolerance. [Copyright &y& Elsevier]
- Published
- 2007
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