Genetic factors in the pathogenesis of gastroesophageal reflux disease

Nocturnal acid breakthrough and esophageal acidification during treatment with dexlansoprazole as compared to omeprazole in patients with gastroesophageal reflux disease

BACKGROUND

Nocturnal acid breakthrough (NAB) may differ based on duration of proton pump inhibitor (PPI) action and Helicobacter pylori (H. pylori) infection; NAB may influence esophageal acidification (EA) and mucosal damage. Dexlansoprazole, a long-acting PPI, was not compared with omeprazole for NAB, gastric acid suppression, and EA in relation to H. pylori infection.

METHODS

In this prospective open-label comparative observational study, gastroesophageal reflux disease (GERD) patients were evaluated using 24-h dual-channel pH-impedance monitoring while on dexlansoprazole (60 mg, n = 39) and omeprazole (20 mg, n = 41) to study the degree of gastric acid suppression, esophageal acid exposure, and NAB (primary outcome measures). H. pylori was detected by rapid urease test and histology.

RESULTS

NAB tended to be frequent with omeprazole than dexlansoprazole (33/41 [80.5%] vs. 23/39 [59%]; p = 0.06). Though nocturnal mean esophageal pH was comparable between the dexlansoprazole and omeprazole groups, its duration was less with the former (181.5 [15.2-334.2] vs. 283 [158-366] min, p = 0.03). NAB was as frequent in the H. pylori-infected than the non-infected group (11/19 [57.9%] vs. 45/61 [73.8%]; p = 0.1). The nocturnal gastric and esophageal pH in the H. pylori-infected group was higher than in the non-infected group (4.6 ± 1.7 vs. 4 ± 1.6, p = 0.157; 6.1 ± 0.6 vs. 5.8 ± 0.6, p = 0.128). Dexlansoprazole tended to increase 24-h and nocturnal mean gastric pH among H. pylori-infected more than omeprazole (5.9 ± 1.1 vs. 4.2 ± 1.7, p = 0.023; 5.7 ± 1.2 vs. 3.8 ± 1.5, p = 0.006).

CONCLUSION

Dexlansoprazole is more effective than omeprazole in suppressing gastric acid secretion, resulting in lesser EA and NAB, particularly in the presence of H. pylori.

Interleukin-1A and interleukin-1B gene polymorphisms in gastroesophageal reflux disease

Inflammation may play contradictory roles in the pathogenesis of gastroesophageal reflux disease (GERD): gastritis decreases gastric output and reduces the risk of esophagitis, while interleukins may favor mucosal inflammation. The inflammation may cause esogastric motility changes and thus increase the risk of esophagitis. Considering the genetic influence of inflammatory response, we looked for the genetic polymorphisms of IL-1 in GERD manifested as reflux esophagitis. This is a prospective study carried out in GERD and healthy controls. We assessed in these groups the following single nucleotide polymorphisms (SNPs): IL-1A (rs1800587), IL-1B (rs16944), IL-1B (rs1143634) and the VNTR for IL-1RN. Both groups were similar according to biographical data. Reflux esophagitis was confirmed by endoscopy and where necessary by pH-impedance monitoring. Reflux esophagitis was associated only with the polymorphism rs16944. No other correlations with the other three genetic polymorphisms were detected. These data suggest that the diverging effects of proinflammatory factors on the upper digestive tract may have deleterious effect on GERD. The IL-1B (rs16944) SNP correlates with reflux esophagitis.

Natural history, pathophysiology and evaluation of gastroesophageal reflux disease

Gastroesophageal reflux disease (GERD) is one of the most common diseases encountered by both internists and gastroenterologists. GERD can cause a wide variety of symptoms ranging from heartburn and regurgitation to more atypical symptoms such as cough, chest pain, and hoarseness. The diagnosis is often times made on the basis of history and clinical symptomatology. The prevalence of GERD is currently estimated to be 8-33% with the incidence of disease only expected to increase over time. Although most cases of GERD can be diagnosed based on symptoms and clinical presentation, the diagnosis of GERD can be challenging when symptoms are atypical. In this review, we provide a comprehensive summary of the epidemiology, pathophysiology, evaluation and diagnosis of gastroesophageal reflux disease.

Risk factors for gastroesophageal reflux disease and analysis of genetic contributors

Gastroesophageal reflux disease (GERD) is a common gastrointestinal disorder with an increasing prevalence. GERD develops when the reflux of stomach contents causes troublesome typical and atypical symptoms and/or complications. Several risk factors of GERD have been identified and evaluated over the years, including a considerable amount of genetic factors. Multiple mechanisms are involved in the pathogenesis of GERD including: (1) motor abnormalities, such as impaired lower esophageal sphincter (LES) resting tone, transient LES relaxations, impaired esophageal acid clearance and delayed gastric emptying; and (2) anatomical factors, such as hiatal hernia and obesity. Genetic contribution seems to play a major role in GERD and GERD- related disorders development such Barrett’s esophagus and esophageal adenocarcinoma. Twin and family studies have revealed an about 31% heritability of the disease. Numerous single-nucleotide polymorphisms in various genes like FOXF1, MHC, CCND1, anti-inflammatory cytokine and DNA repair genes have been strongly associated with increased GERD risk. GERD, Barrett’s esophagus and esophageal adenocarcinoma share several genetic loci. Despite GERD polygenic basis, specific genetic loci such as rs10419226 on chromosome 19, rs2687201 on chromosome 3, rs10852151 on chromosome 15 and rs520525 on the paired related homeobox 1 gene have been mentioned as potential risk factors. Further investigation on the risk genes may elucidate their exact function and role and demonstrate new therapeutic approaches to this increasingly common disease.

Polymorphisms of the FOXF1 and MHC locus genes in individuals undergoing esophageal acid reflux assessments

Gastroesophageal reflux disease (GERD) may lead to Barrett's esophagus (BE). Previously, a large genome-wide association study found two germline markers to be associated with BE, FOXF1 rs9936833 (C allele) and MHC rs9257809 (A allele). This study evaluated whether these two polymorphisms are associated with gastroesphageal acid reflux as measured by 24-hour pH testing. Patients with acid reflux symptoms referred for esophageal manometry and 24-hour pH monitoring at University Health Network (Toronto, ON) were enrolled. DNA extracted from blood was genotyped using a Taqman Polymerase Chain Reaction (PCR) assay. DeMeester scores of ≥14.7 or prior evidence of reflux esophagitis on endoscopy defined individuals with esophageal acid reflux. Logistic regression analysis, adjusted for clinical risk factors, was used to calculate odds ratios with 95% confidence intervals for each polymorphism in relation to the presence of acid reflux. Of 182 patients, the median age was 50 years and 62% were female; 95 (52%) met the definition of GERD. In the multivariable analysis, both FOXF1 rs9936833 (OR = 1.82; 95%CI: 1.12-2.96; P = 0.02) and MHC rs9257809 (OR = 9.36; 95%CI: 2.92-29.99; P < 0.001) remained significantly associated with presence of acid reflux. When both polymorphisms were placed in the same model, the adjusted ORs were 2.10 (95%CI: 1.24-3.53; P = 0.005) and 10.95 (95%CI: 3.32-36.09; P < 0.001), respectively. The association for risk allele C in FOXF1 rs9936833 and risk allele A in MHC rs9257809 with the presence of acid reflux suggests a potential pathophysiologic mechanism for the role of genetic influences in BE development.

Insights into the genetics of gastroesophageal reflux disease (GERD) and GERD-related disorders

Gastroesophageal reflux disease (GERD) is associated with obesity and hiatal hernia, and often precedes the development of Barrett's esophagus (BE) and esophageal adenocarcinoma (EA). Epidemiological studies show that the global prevalence of GERD is increasing. GERD is a multifactorial disease with a complex genetic architecture. Genome-wide association studies (GWAS) have provided initial insights into the genetic background of GERD. The present review summarizes current knowledge of the genetics of GERD and a possible genetic overlap between GERD and BE and EA. The review discusses genes and cellular pathways that have been implicated through GWAS, and provides an outlook on how future molecular research will enhance understanding of GERD pathophysiology.

Incidence of gastroesophageal reflux disease in Uygur and Han Chinese adults in Urumqi

AIM: To investigate the incidence of gastroesophageal reflux disease (GERD) and its related risk factors in Uygur and Han Chinese adult in Urumqi, China.

METHODS: A population-based cross-sectional survey was undertaken in a total of 972 Uygur (684 male and 288 female) aged from 24 to 61 and 1023 Han Chinese (752 male and 271 female) aged from 23 to 63 years. All participants were recruited from the residents who visited hospital for health examination from November 2011 to May 2012. Each participant signed an informed consent and completed a GERD questionnaire (Gerd Q) and a lifestyle-food frequency questionnaire survey. Participants whose Gerd Q score was ≥ 8 and met one of the following requirements would be enrolled into this research: (1) being diagnosed with erosive esophagitis (EE) or Barrett’s esophagus (BE) by endoscopy; (2) negative manifestation under endoscopy (non-erosive reflux disease, NERD) with abnormal acid reflux revealed by 24-h esophageal pH monitoring; and (3) suffering from typical heartburn and regurgitation with positive result of proton pump inhibitor test.

RESULTS: According to Gerd Q scoring criteria, 340 cases of Uygur and 286 cases of Han Chinese were defined as GERD. GERD incidence in Uygur was significantly higher than in Han Chinese (35% vs 28%, χ² = 11.09, P < 0.005), Gerd Q score in Uygur was higher than in Han Chinese (7.85 ± 3.1 vs 7.15 ± 2.9, P < 0.005), and Gerd Q total score in Uygur male was higher than in female (8.15 ± 2.8 vs 6.85 ± 2.5, P < 0.005). According to normalized methods, 304 (31%) cases of Uygur were diagnosed with GERD, including 89 cases of EE, 185 cases of NERD and 30 cases of BE; 256 (25%) cases of Han Chinese were diagnosed with GERD, including 90 cases of EE, 140 cases of NERD and 26 cases of BE. GERD incidence in Uygur was significantly higher than in Han Chinese (31% vs 25%, χ² = 9.34, P < 0.005) while the incidences were higher in males of both groups than in females (26% vs 5% in Uygur, χ² = 35.95, P < 0.005, and 19.8% vs 5.2% in Han, χ² = 5.48, P < 0.025). GERD incidence in Uygur male was higher than in Han Chinese male (26% vs 19.8%, χ² = 16.51, P < 0.005), and incidence of NERD in Uygur was higher than in Han Chinese (χ² = 10.06, P < 0.005). Occupation (r = 0.623), gender (r = 0.839), smoking (r = 0.322), strong tea (r = 0.658), alcohol drinking (r = 0.696), meat-based diet (mainly meat) (r = 0.676) and body mass index (BMI) (r = 0.567) were linearly correlated with GERD in Uygur (r = 0.833, P = 0.000); while gender (r = 0.957), age (r = 0.016), occupation (r = 0.482), strong tea (r = 1.124), alcohol drinking (r = 0.558), meat diet (r = 0.591) and BMI (r = 0.246) were linearly correlated with GERD in Han Chinese (r = 0.786, P = 0.01). There was no significant difference between Gerd Q scoring and three normalized methods for the diagnosis of GERD.

CONCLUSION: GERD is highly prevalent in adult in Urumqi, especially in Uygur. Male, civil servant, smoking, strong tea, alcohol drinking, meat diet and BMI are risk factors correlated to GERD.