G-Protein Beta3 Subunit C825T Polymorphism in Patients With Overlap Syndrome of Functional Dyspepsia and Irritable Bowel Syndrome

Characterization of Digestive Manifestations in Patients with Impaired PTH/PTHrP Signaling Disorder/Pseudohypoparathyroidism

INTRODUCTION

Pseudohypoparathyroidism, newly classified as inactivating PTH/PTHrP signaling disorder (iPPSD) type 2 or type 3, is a rare disease caused by defects in the GNAS imprinted gene that encodes Gsα. The most common phenotype comprises resistance to hormones binding to G protein-coupled receptors such as PTH, PTHrP, or TSH, subcutaneous ossifications, short stature, brachydactyly, and early onset obesity. Uncommon features have been described including sleep apnea, asthma, and resistance to calcitonin. At the national French reference center for rare calcium and phosphate metabolism diseases, a large cohort of patients with iPPSD type 2 and type 3 is followed. Interestingly, digestive manifestations and in particular intractable constipation were regularly reported by families of children with iPPSD type 2 or type 3.

OBJECTIVE

The aim of our study was therefore to specify the frequency and characteristics of digestive manifestations in children followed up for iPPSD2 or iPPSD3 in our reference center.

MATERIAL AND METHODS

Thirty-six patients aged between 2 and 18 years (32 followed up for iPPSD2 and 4 for iPPSD3) were included. Parents completed a specific questionnaire to assess any digestive disorders in their child. The diagnosis of constipation was established using the Bristol visual scale in the event of a score of less than 2 according to stool appearance.

RESULTS

Parents reported constipation through the questionnaires in 22/36 (over 60%) of the children. It was the most frequently reported digestive disorder. Among these 22 children, 19 (87%) had a Bristol score for stool shape and texture between 1 and 2 on a scale of 7, confirming constipation. Dedicated treatment had been initiated for 10 (55%) of them, yet only 3 families (16%) considered this treatment effective. Neonatal vomiting and eating disorders, such as lack of satiety or food selectivity, were also noted in 18 (50%) of patients, as was gastroesophageal reflux present in the neonatal period in 14 (40%) of children. There were no significant differences according to the type of iPPSD or patient age.

CONCLUSION

Our work shows for the first time that digestive manifestations, including constipation, occur frequently in children followed for iPPSD, suggesting a potential role of Gsα and G protein receptors in the digestive tract. It is well known that constipation and digestive symptoms alter quality of life. Early management is therefore essential to improve the quality of life of children followed for iPPSD. Our data need to be confirmed on a larger cohort.

Gene Polymorphisms and Susceptibility to Functional Dyspepsia: A Systematic Review and Meta-Analysis

Functional dyspepsia (FD) is a common chronic gastrointestinal disorder with a complex, undefined mechanism. Clustering of patients with FD in families highlights the role of genetic factors in the pathogenesis of FD. We performed a systematic review and meta-analysis to clarify the associations between specific gene polymorphisms and FD susceptibility. PubMed, EMBASE, the Cochrane Library, and HuGE database were searched. An additive model was adopted to determine whether previous studied genes are associated with FD susceptibility. Carriers of minor allele in GNB3 825C>T (OR = 1.15, 95% CI 0.99-1.34, P = 0.07), SCL6A4 5HTTLPR (OR = 0.92, 95% CI 0.75-1.12, P = 0.40), and CCK-1R 779T>C (OR = 0.86, 95% CI 0.72-1.03, P = 0.09) genes failed to demonstrate susceptibility to FD. In a subgroup analysis, only minor allele (T) in GNB3 825C>T was associated with an increased susceptibility to the epigastric pain syndrome subtype (OR = 1.34, 95% CI 1.10-1.63, P = 0.003). Our meta-analysis based on available studies using an additive model failed to show that GNB3, SCL6A4, and CCK-1R polymorphisms are associated with FD susceptibility.

Immunopathological and molecular basis of functional dyspepsia and current therapeutic approaches

INTRODUCTION

Functional dyspepsia (FD) is widespread with 20% prevalence worldwide and a significant economic burden due to health care cost and constraints on daily activities of patients. Despite extensive investigation, the underlying causes of dyspepsia in a majority of patients remain unknown. Common complaints include abdominal discomfort, pain, burning, nausea, early satiety, and bloating. Motor dysfunction of the gut was long considered a major cause, but recent investigations suggest immune-based pathophysiological and molecular events in the duodenum are more probable contributing factors. Areas Covered: Inflammatory mediators and immune cells including duodenal eosinophils, intraepithelial lymphocytes, and T-cells have been implicated in the underlying cause of disease process, as have genetic factors. In this article, we critically reviewed findings, identified gaps in knowledge and suggested future directions for further investigation to identify targets and develop better therapeutic approaches. Expert commentary: Impaired gastric accommodation, slow gastric emptying, and increased visceral sensitivity have long been thought of as main causal factors of FD. However, more recent identification of eosinophilic degranulation and recruitment of T cells that induce mild duodenal inflammation are giving rise to new insights into immune-mediated pathophysiology. These insights offer promising avenues to explore for immune-mediated therapy in the future.

G protein beta 3(GNβ3) C825T polymorphism and irritable bowel syndrome susceptibility: an updated meta-analysis based on eleven case-control studies

Several studies have reported an association between GNβ3 C825T polymorphism and irritable bowel syndrome (IBS). However, the results remain inconclusive and controversial, particularly for the data derived from different ethnicities and IBS subtypes. Therefore, we performed an updated meta-analysis to evaluate this association. All eligible case-control studies that met the search criteria were retrieved from multiple databases, and eleven case-control studies were included for detailed evaluation. The pooled odds ratios (ORs) with 95% confidence intervals (95% CIs) were calculated to assess the strengths of the association between GNβ3 C825T polymorphism and susceptibility to IBS and its subtypes. Our meta-analysis found no significantly associations of GNβ3 C825T polymorphism with IBS risk in all populations. Whereas the C allele was demonstrated to be a decreased risk factor for constipation predominant IBS (IBS-C) in allele model. Additionally, the CC genotype was found to be associated with increased diarrhea predominant IBS (IBS-D) risk in recessive model. Subgroup analysis by ethnicity revealed that these associations held true for the Asian subpopulation. In conclusion, this meta-analysis suggests the C allele of GNβ3 C825T might be associated with a decreased risk of IBS-C, and the CC genotype of GNβ3 might be associated with increased IBS-D risk.

Functional dyspepsia susceptibility is related to CD14, GNB3, MIF, and TRPV1 gene polymorphisms in the Greek population

BACKGROUND

Functional dyspepsia (FD) susceptibility might be influenced by polymorphisms of genes related to inflammation (CD14, macrophage migration inhibitory factor [MIF]), motor (GNB3), and sensory dysfunction (GNB3, TRPV1). We examined the association between CD14 rs2569190, GNB3 rs5443, MIF rs222747, and TRPV1 rs755622 gene polymorphisms with FD (Rome III criteria) in the Greek population.

METHODS

We genotyped 174 dyspeptics (115 with epigastric pain syndrome; 41% Helicobacter pylori positive) and 181 controls using polymerase chain reaction-based methods and we measured disease symptoms' burden with a modified Gastrointestinal Symptoms Related Scale.

KEY RESULTS

Homozygous for the TT genotype and the T allele of the CD14 gene were significantly associated (OR [95% CI]) with FD (2.65 [1.42-4.94] and 1.67 [1.23-2.26], respectively). The CT, TT genotypes, and T allele frequencies of GNB3 showed also significant association with FD (2.18 [1.35-3.54], 3.46 [1.30-9.23], and 2.18 [1.48-3.19]). While heterozygous GC MIF genotype was more common in dyspeptics (1.67 [1.07-2.60]), homozygous CC genotype and the C allele of TRPV1 gene were more prevalent in controls (0.47 [0.25-0.87] and 0.69 [0.51-0.92], respectively). None of the gene polymorphism was related either to dyspepsia clinical syndrome type or to the H. pylori infection. Among dyspeptics, CD14 TT genotype was related to lower epigastric pain burden score (p<.011); CD14 CT genotype was related to higher epigastric burning and nausea burden scores (p<.04) while belching score was lower (p=.027) in MIF CG dyspeptics.

CONCLUSION & INFERENCES

Functional dyspepsia susceptibility is related to CD14, GNB3, MIF, and TRPV1 gene polymorphisms, while CD14 and MIF gene variants are also associated with dyspepsia symptoms burden.

Functional dyspepsia is associated with GNβ3 C825T and CCK-AR T/C polymorphism

BACKGROUND

A polymorphism (C825T) in G-protein β polypeptide-3 (GNβ3) gene alters intracellular signal transduction, which may cause motor or sensory abnormalities in the gastrointestinal tract. Cholecystokinin-A receptor (CCK-AR) gene T/C polymorphism is associated with a defective splicing of the primary transcript of CCK-AR mRNA, which may modulate satiety signal and delay gastric emptying. Therefore, we evaluated the role of these polymorphisms in patients with functional dyspepsia (FD) as compared with healthy controls (HC).

PATIENTS AND METHODS

A total of 237 consecutive patients with FD (Rome III) and 250 HC were genotyped for GNβ3 C825T and CCK-AR T/C polymorphisms (PCR-RFLP).

RESULTS

Patients with FD [173 (73%) men, age: 38 ± 12 years] were comparable with HC [195 (78%) men, age: 37 ± 12 years] with respect to age and sex. Out of 237 patients, 26 (11%) had epigastric pain syndrome (EPS), 55 (23.2%) had postprandial distress syndrome (PDS), and 156 (65.8%) had EPS-PDS overlap. Among 237 patients with FD, TT genotype (associated with increased intracellular signal transduction) of GNβ3 C825T polymorphism was more common among patients than among HC [26 (11%) vs. 12 (4.8%), P=0.014; odds ratio (OR): 2.47, 95% confidence interval (CI): 1.2-5.1]. CC (variant) genotype of CCK-AR T/C polymorphism was infrequent among patients than among HC [19 (8%) vs. 46 (18.4%), P=0.001; OR: 0.36, 95% CI: 0.19-0.66]. However, these polymorphisms were comparable among patients with different subtypes of FD (P=0.80 and 0.44).

CONCLUSION

TT genotype of GNβ3 C825T is more common among patients with FD than among HC, suggesting that increased signal transduction associated with this genotype may be important in its pathophysiology. However, CCK-AR polymorphism is protective against FD.

Genetics and pharmacogenetics of aminergic transmitter pathways in functional gastrointestinal disorders

Functional gastrointestinal disorders (FGIDs) are highly prevalent syndromes, without evident underlying organic causes. Their pathogenesis is multifactorial in nature, with a combination of environmental and genetic factors contributing to their clinical manifestations, for which most of current treatments are not satisfactory. It is acknowledged that amine mediators (noradrenaline, dopamine and serotonin) play pivotal regulatory actions on gut functions and visceral sensation. In addition, drugs of therapeutic interest for FGIDs act on these transmitter pathways. The present article reviews current knowledge on the impact of genetics and pharmacogenetics of aminergic pathways on FGID pathophysiology, clinical presentations, symptom severity and medical management, in an attempt of highlighting the most relevant evidence and point out issues that should be addressed in future investigations.

The C825T Polymorphism of the G-Protein β3 Gene as a Risk Factor for Functional Dyspepsia: A Meta-Analysis

Background. Functional dyspepsia (FD) is a functional upper gastrointestinal disorder with significant morbidity and medical costs. Previous studies investigated the association of G-protein β3 (GNB3) genetic polymorphisms with FD but with inconsistent results. Therefore, we performed a meta-analysis to derive a precise estimation of the relationship between GNB3 polymorphisms and FD. Methods. We searched different databases including PubMed, EMBASE, CNKI, and the Ovid Library to gather eligible studies on GNB3 polymorphisms and FD. The association was assessed by the odds ratio (OR) with 95% confidence intervals (CI). Results. We identified 12 studies with 1109 cases and 2853 controls for the analysis. We found no associations of GNB3 C825T polymorphism with FD in the overall population (T versus C, OR = 1.06, 95% CI: 0.96-1.18, P = 0.26; TT versus CC + CT, OR = 1.16, 95% CI: 0.97-1.39, P = 0.11; TT + CT versus CC, OR = 1.01, 95% CI: 0.77-1.31, P = 0.96; TT versus CC, OR = 1.15, 95% CI: 0.93-1.44, P = 0.20). Subgroup analyses by genotyping method indicated that the magnitude of association was strengthened for additive model (OR = 1.15, 95% CI: 1.07-2.24, P = 0.02). Sensitivity analysis did not reveal significant associations under all models. Conclusions. This meta-analysis demonstrates that GNB3 C825T polymorphism may not be a risk factor for FD.

Genetic epidemiology of irritable bowel syndrome

Irritable bowel syndrome (IBS) is the most common functional gastrointestinal disorder characterized by presence of abdominal pain or discomfort associated with altered bowel habits. It has three main subtypes - constipation predominant IBS (C-IBS), diarrhea predominant IBS (D-IBS) and IBS with mixed features of both diarrhea as well as constipation (M-IBS). Its pathophysiology and underlying mechanisms remain elusive. It is traditionally believed that IBS is a result of multiple factors including hypersensitivity of the bowel, altered bowel motility, inflammation and stress. Initial studies have shown familial aggregation of IBS suggesting shared genetic or environmental factors. Twin studies of IBS from different parts of world have shown higher concordance rates among monozygotic twins than dizygotic twins, and thus suggesting a genetic component to this disorder. Multiple studies have tried to link single-nucleotide polymorphisms (SNPs) to IBS but there is little evidence that these SNPs are functional. Various molecules have been studied and investigated by the researchers. Serotonin, a known neurotransmitter and a local hormone in the enteric nervous system, has been most extensively explored. At this time, the underlying gene pathways, genes and functional variants linked with IBS remain unknown and the promise of genetically-determined risk prediction and personalize medicine remain unfulfilled. However, molecular biological technologies continue to evolve rapidly and genetic investigations offer much promise in the intervention, treatment and prevention of IBS.

Reduction in duodenal endocrine cells in irritable bowel syndrome is associated with stem cell abnormalities

AIM: To determine whether the decreased density of duodenal endocrine cells in irritable bowel syndrome (IBS) is associated with abnormalities in stem cell differentiation.

METHODS: The study sample comprised 203 patients with IBS (180 females and 23 males with a mean age of 36 years) and a control group of 86 healthy subjects without gastrointestinal complaints (77 females and 9 males with a mean age of 38 years). The patients included 80 with mostly diarrhoea (IBS-D), 47 with both diarrhoea and constipation (IBS-M), and 76 with mostly constipation (IBS-C). Both the patients and controls underwent gastroscopy and four biopsy samples were taken from the descending part of the duodenum, proximal to the papilla of Vater. The biopsy samples were sectioned and immunostained for Musashi 1 (Msi-1), neurogenin 3 (NEUROG3), secretin, cholecystokinin (CCK), gastric inhibitory peptide (GIP), somatostatin and serotonin. Immunostaining was performed with an ultraView Universal DAB Detection Kit (v1.02.0018, Venata Medical Systems, Basal, Switzerland) using the BenchMark Ultra immunohistochemistry/in situ hybridization staining module (Venata Medical Systems). Endocrine cell densities were quantified by computerized image analysis using the Olympus cellSens imaging program.

RESULTS: The densities of Msi-1 and NEUROG3 cells were significantly lower in IBS patients, regardless of the subtype, than in the controls (77 ± 17 vs 8 ± 2; P = 0.0001, and 351 ± 33 vs 103 ± 22; P = 0.00002, respectively). Furthermore, the densities of secretin, and CCK cells were significantly lower in patients with diarrhoea as the predominant IBS symptom (IBS-D) than in the controls (161 ± 11 vs 88 ± 8; P = 0.00007, and 325 ± 41 vs 118 ± 10; P = 0.00006, respectively), but not in patients with constipation as the predominant IBS symptom (IBS-C) or those with both diarrhoea and constipation (IBS-M). The GIP cell density was significantly reduced in both IBS-D (152 ± 12 vs 82 ± 7; P = 0.00003), and IBS-C (152 ± 12 vs 107 ± 8; P = 0.01), but not in IBS-M. The densities of somatostatin cells in the controls and the IBS-total, IBS-D, IBS-M and IBS-C patients were 81 ± 8, 28 ± 3, 20 ± 4, 37 ± 5 and 28 ± 4 cells/mm² epithelium, respectively. The density of somatostatin cells was lower in IBS-total, IBS-D, IBS-M and IBS-C patients than in the controls (P = 0.00009, 0.00006, 0.009 and 0.00008, respectively). The density of serotonin cells did not differ between IBS patients and controls.

CONCLUSION: The reduction in duodenal endocrine cells in IBS patients found in this study is probably attributable to the reduction in cells expressing Msi-1 and NEUROG3.

Leu72Met408 Polymorphism of the Ghrelin Gene Is Associated With Early Phase of Gastric Emptying in the Patients With Functional Dyspepsia in Japan

Background/Aims

There are no available data about the relationship between ghrelin gene genotypes and early phase of gastric emptying in functional dyspepsia (FD) as defined by Rome III classification.

Methods

We enrolled 74 patients presenting with typical symptoms of FD and 64 healthy volunteers. Gastric motility was evaluated using the ¹³C-acetate breath test. We used Rome III criteria to evaluate upper abdominal symptoms and self-rating questionnaires for depression (SRQ-D) scores to determine status of depression. The Arg51Gln (346G>A), preproghrelin (3056T>C), Leu72Met (408C>A), Gln90Leu (3412T>A) and G-protein β3 (825C>T) polymorphisms were analyzed in the DNA from blood samples of enrolled subjects. Genotyping was performed by polymerase chain reaction.

Results

There was a significant relationship between the Gln90Leu3412 genotype and SRQ-D score in FD patients (P = 0.009). Area under the curve at 15 minutes (AUC₁₅) value was significantly associated with the Leu72Met408 genotype (P = 0.015) but not with entire gastric emptying.

Conclusions

The Leu72Met (408C>A) single nucleotide polymorphism was significantly associated with early phase of gastric emptying in FD patients. Further studies will be necessary to clarify the association between ghrelin gene single nucleotide polymorphisms and early phase of gastric emptying in FD patients.

G protein β3 subunit polymorphism and long-term prognosis of functional dyspepsia

Background/Aims

A link between G protein β3 (GNB3) polymorphism and functional dyspepsia (FD) has been suggested. The aim of this study was to determine the role of GNB3 polymorphism in the long-term prognosis of FD in Koreans.

Methods

FD patients and normal healthy controls were recruited from patients who visited our center between December 2006 and June 2007. All of the subjects completed Rome III questionnaires before undergoing upper gastrointestinal endoscopy and colonoscopy. Genomic DNA was extracted for GNB3 genotyping. After 5 years, the subjects were reevaluated using the same questionnaires.

Results

GNB3 825T carrier status was significantly related to FD in Koreans (p=0.04). After 5 years, 61.0% of the initial FD patients and 12.2% of the initial normal subjects were diagnosed with FD (odds ratio [OR], 11.7; 95% confidence interval [CI], 4.3 to 31.1; p<0.001). Regardless of the GNB3 genotype (p=0.798), female sex was strongly correlated with FD after 5 years (OR, 3.3; 95% CI, 1.2 to 9.1; p=0.017).

Conclusions

The T allele of GNB3 is linked to FD in Koreans but does not predict long-term prognosis. Female sex is related to a higher prevalence of FD after 5 years.

Genetic polymorphism in pathogenesis of irritable bowel syndrome

Irritable bowel syndrome (IBS) is a complex symptom-based disorder without established biomarkers or putative pathophysiology. IBS is a common functional gastrointestinal disorder which is defined as recurrent abdominal pain or discomfort that has at least two of the following symptoms for 3 d per month in the past 3 mo according to ROME III: relief by defecation, onset associated with a change in stool frequency or onset with change in appearance or form of stool. Recent discoveries revealed genetic polymorphisms in specific cytokines and neuropeptides may possibly influence the frequencies and severity of symptoms, as well as the therapeutic responses in treating IBS patients. This review gives new insights on how genetic determinations influence in clinical manifestations, treatment responses and potential biomarkers of IBS.

Overlap in patients with dyspepsia/functional dyspepsia

Patients with dyspepsia/functional dyspepsia (FD) show frequent overlapping of other gastrointestinal (GI) diseases, such as irri-table bowel syndrome, and non-GI diseases, in addition to internal subgroup overlapping. These overlap patients have more frequent or more severe symptoms, poorer health-related quality of life and higher somatization scores, and they are more like-ly to experience anxiety, depression or insomnia compared to non-overlap patients. The higher prevalence of overlap in patients with dyspepsia/FD is not by chance, indicating common pathogeneses, including visceral hypersensitivity, altered GI motility, in-fection, and stressful early life events. There are few clinical trials targeting overlap in patients with dyspepsia/FD, and no ther-apeutic strategy has been established. Further studies in this research area are needed. In this review, we describe the epidemi-ology, pathogenesis and treatment of overlap in patients with dyspepsia/FD.(J Neurogastroenterol Motil 2014;20:447-457).

Association of SLC6A4 5-HTTLPR and TRPV1 945G>C with functional dyspepsia in Korea

BACKGROUND AND AIM

The association of various genetic polymorphisms with functional dyspepsia (FD) has been suggested, but the results were still controversial. The aim of the present study was to assess the association of GNB3 825C>T, SLC6A4 5-HTTLPR, ADRA2A-1291C>G, CCK-1R intron 779T>C, and TRPV1 945G>C polymorphisms with FD based on Rome III criteria in Korea.

METHODS

Study subjects were prospectively recruited from visitors to Seoul National University Bundang Hospital between 2009 and 2012. One hundred and twelve FD patients and 269 controls were enrolled.

RESULTS

In SLC6A4 5-HTTLPR polymorphism, the frequency of S/S genotype was significantly lower than that of L/L + L/S genotype in FD compared to controls (P < 0.05). After stratification according to Helicobacter pylori infection, the S/S genotype was significantly associated with H. pylori-positive epigastric pain syndrome (EPS) patients (adjusted odds ratio (OR) 0.46; 95% confidence interval (CI) 0.22-0.99; P = 0.048). In TRPV1 945G>C polymorphism, the frequency of C/C genotype was lower in FD compared to controls (P = 0.057). The C carrier and C/C genotype was significantly associated with postprandial distress syndrome (PDS) and EPS, respectively (adjusted OR 0.47 and 0.43; 95% CI 0.25-0.90 and 0.20-0.93; P = 0.021 and 0.033). After stratification, the significant associations remained in H. pylori-positive PDS and EPS patients (adjusted OR 0.37 and 0.28; 95% CI 0.16-0.88 and 0.09-0.85; P = 0.024 and 0.025).

CONCLUSIONS

The genetic polymorphism of SLC6A4 5-HTTLPR and TRPV1 945G>C could be one of the pathophysiological factors of FD, especially in the case of H. pylori-positive patients in Korea.

[Current issues in functional dyspepsia]

Functional dyspepsia is one of the most common gastrointestinal disorders encountered in clinical practice. Functional dyspepsia is currently defined by Rome III criteria as the chronic dyspeptic symptoms (postprandial fullness, early satiety, epigastric pain or burning) in the absence of underling structural or metabolic disease that readily explain the symptoms. According to the Rome III consensus, functional dyspepsia can be subdivided into postprandial distress syndrome (PDS) and epigastric pain syndrome (EPS). Although the Rome III criteria have been published more than 8 years ago, not much effort has been put into validating these criteria and direct scientific evidence supporting the validity of the subdividing functional dyspepsia into PDS and EPS are lacking. This article is intended to review the validity of the Rome III criteria on the subdivisions of functional dyspepsia, i.e. PDS and EPS. The impact of sleep disorder, Helicobacter pylori-associated dyspepsia, and the emerging drug therapies in functional dyspepsia will also be discussed in this article.

Stomach antral endocrine cells in patients with irritable bowel syndrome

To the best of our knowledge, stomach antral endocrine cells have not previously been investigated in patients with irritable bowel syndrome (IBS). Thus, in the present study, 76 patients with IBS were examined (designated as IBS-total). Diarrhoea was the predominant symptom in 26 of these patients (IBS-D), while in 21 patients, the predominant symptoms were both diarrhoea and constipation (IBS-M) and in 29 patients the predominant symptom was constipation (IBS-C). Forty-three healthy subjects were enrolled as the controls. Stomach antral biopsy samples obtained from all of the subjects were immunostained using the avidin-biotin-complex method for serotonin, gastrin, somatostatin and serotonin transporter (SERT). The immunopositive cell densities and immunoreactivity intensities were determined by computer-aided image analysis. The density of the serotonin-immunoreactive cells was significantly decreased in the IBS-M patients and increased in the IBS-C patients relative to the controls. The immunoreactivity intensity did not differ significantly between the controls and IBS-total. The density of the gastrin-immunoreactive cells was significantly greater in the IBS-D, IBS-M and IBS-C patients than in the controls. The immunoreactivity intensity of gastrin was significantly greater in the IBS-D patients than in the controls. The density of the somatostatin-immunoreactive cells cells was significantly lower in the IBS-total, IBS-D, IBS-M and IBS-C patients than in the controls. The immunoreactivity intensities of both somatostatin and SERT did not differ significantly between the controls and IBS-total. The increase in gastrin cell density and the decrease in somatostatin cell density in all IBS subtypes may cause high levels of gastric secretion, which may in turn contribute to the high incidence of dyspepsia and gastro-oesophageal reflux observed in patients with IBS.

Association of genetic variants in GNβ3 with functional dyspepsia: a meta-analysis

BACKGROUND

Functional dyspepsia (FD) is a functional upper gastrointestinal disorder. The etiology and pathogenesis of FD remain unclear, with genetic factors playing an important role. Previous studies investigated the association of C825T in GNβ3 with FD, with conflicting results reported.

AIMS

The aim of this meta-analysis is to assess the association of genetic variants in GNβ3 with FD.

METHODS

We performed a systematic literature search in PubMed, Cochrane Library, Google Scholar, and Web of Knowledge, and conducted a meta-analysis to assess the association of C825T in GNβ3 with FD. For sensitivity analysis, we analyzed the association between C825T and subtypes of FD. We also performed meta-analyses separately for individual ethnic groups/countries of origin.

RESULTS

A total of eight studies met the eligibility criteria and were included in our analyses. Our meta-analysis finds no association between 825CC and FD (OR 1.19, 95% CI 0.84-1.67, p = 0.328). However, the association is significant under an additive model (OR 0.59, 95% CI 0.38-0.92, p = 0.018). Sensitivity analysis indicated a significant association of C825T with FD in participants from Korea but not in those from Japan, Europe, or the United States. We also detected a significant association of this SNP with dysmotility.

CONCLUSIONS

The genetic variant C825T in GNβ3 is significantly associated with FD under an additive model and the association is race-specific. Further studies with larger samples sizes are needed to validate our findings and to explore the potential mechanism underlying the association.

Association Between SLC6A4 Serotonin Transporter Gene Lainked Polymorphic Region and ADRA2A -1291C>G and Irritable Bowel Syndrome in Korea

Background/Aims

Despite numerous studies on the relation of genetic polymorphisms with irritable bowel syndrome (IBS), the results still remain inconclusive. The aim of this study was to assess the possible association between SLC6A4 serotonin transporter gene linked polymorphic region (5-HTTLPR), ADRA2A −1291C>G, GNB3 825C>T, CCK1R intron 779T>C and TRPV1 945G>C polymorphisms and IBS based on Rome III criteria in Korea.

Methods

Study subjects were prospectively recruited from visitors to Seoul National University Bundang Hospital between July 2009 and January 2014. Ninety-nine IBS patients and 171 healthy controls were enrolled. Polymorphisms of above-mentioned 5 genes were genotyped. Serum serotonin from 101 participants was measured by ELISA and compared according to SLC6A4 5-HTTLPR polymorphisms and IBS subtypes.

Results

Regarding SLC6A4 5-HTTLPR polymorphism, L/L genotype was significantly associated with the total IBS, constipation predominant IBS (IBS-C) and mixture of diarrhea and constipation IBS (IBS-M) (adjusted OR: 4.35, 95% CI: 1.04–16.67; adjusted OR: 11.11, 95% CI: 1.69–50.00 and adjusted OR: 5.56, 95% CI: 1.05–33.33, respectively). Carrying ADRA2A −1291G allele was significantly associated with total IBS and diarrhea predominant IBS (adjusted OR: 3.37, 95% CI: 1.16–9.77 and adjusted OR: 5.64, 95% CI: 1.18–27.01, respectively). IBS-C patients showed reduced level of serum serotonin compared to controls and patients with diarrhea predominant IBS (50.2 ng/mL vs. 69.0 ng/mL and 92.9 ng/mL, P = 0.017 and P = 0.001, respectively).

Conclusions

Genetic polymorphisms of SLC6A4 5-HTTLPR and ADRA2A −1291C>G could be one of the pathophysiological factors of IBS in Korea. Reduced serum serotonin shown in the IBS-C group suggested a role of serotonin in IBS, but large study is needed for confirming genotypic difference in serum serotonin level.

A genetic association study of single nucleotide polymorphisms in GNβ3 and COMT in elderly patients with irritable bowel syndrome

Background

Several polymorphisms have been reported to be associated with irritable bowel syndrome (IBS), including C825T, the single nucleotide polymorphism (SNP), responsible for a truncated G protein β3 subunit (GNβ3), and the Vall158Met substitution in catechol-O-methyltransferase (COMT). We investigated the association between these mutations and the prevalence of IBS in 66 elderly Chinese patients.

Material/Methods

Sixty-six patients (over age 60 years) were diagnosed with IBS according to the Rome III criteria, and divided into 3 groups based on symptom presentation. The groups consisted of 7 patients with constipation, 46 patients with diarrhea, and 13 patients with both or neither symptoms. We enrolled 115 age-matched individuals without IBS as the control group. All patients were evaluated by using the Geriatric Depression Scale, disease progression was recorded, and GNβ3 and COMT were genotyped by PCR.

Results

There was no significant difference in GNβ3 C825T genotype distribution and allele frequency between the 2 groups. In contrast, compared with control subjects, COMT 158Met was significantly more prevalent in the IBS group (P=0.040) and significantly more prevalent in patients with diarrhea (P=0.029). 158Met was also more prevalent in those patients who had experienced symptoms for over 5 years (P=0.022).

Conclusions

In elderly Chinese patients, the 158Met SNP in COMT is associated with IBS pathogenesis, but the GNβ3-C825T SNP is not associated with IBS pathogenesis.

No association of G-protein beta polypeptide 3 polymorphism with irritable bowel syndrome: Evidence from a meta-analysis

AIM: To clarify the associations between G-protein beta polypeptide 3 (GNB3) C825T polymorphism and risk of the irritable bowel syndrome (IBS) by a meta-analysis.

METHODS: We searched relevant studies in PubMed, EMBASE, CNKI, Google Scholar, Ovid and Cochrane library prior to October 2013. The strengths of the associations between GNB3 C825T polymorphism and IBS risk were estimated by odds ratios (ORs) with 95% confidence interval (CIs).

RESULTS: We identified seven case-control studies with 1085 IBS cases and 1695 controls for the analysis. We found no significantly associations of GNB3 C825T polymorphism with IBS risk in the overall population (CC vs TT, OR = 1.12, 95%CI: 0.86-1.45; CC + CT vs TT, OR = 1.17, 95%CI: 0.92-1.49; TT + CT vs CC, OR = 0.93, 95%CI: 0.80-1.08; C vs T, OR = 1.08, 95%CI: 0.97-1.21). Subgroup analysis did not reveal significant associations either in Asian population or Caucasian population. The pooled results of four studies fail to show associations of GNB3 C825T polymorphism with subtypes of IBS (constipation-dominant type, diarrhea-dominant type and mixed type).

CONCLUSION: The present study suggests no associations of GNB3 C825T polymorphism with IBS risk.

Current status of functional dyspepsia in Korea

Dyspepsia refers to group of commonly occurring upper gastrointestinal symptoms. The majority of patients with dyspepsia suffer from functional (nonulcer) dyspepsia. Although there is a lack of epidemiological data from population-based or patient cohort studies in Korea, the current understanding of this condition has been updated using data from various recent research studies, which have facilitated the development of clinical guidelines for functional dyspepsia. According to a survey using the Rome III criteria, more than 40% of respondents who visited primary clinics and tertiary hospitals were defined as having functional dyspepsia, most of who were within a subgroup of patients with postprandial distress syndrome. In addition, a population-based cross-sectional survey revealed considerable overlap between functional dyspepsia and other functional gastrointestinal disorders, including gastroesophageal reflux disease (especially nonerosive reflux disease) and irritable bowel syndrome. In contrast to the results of Western trials, there is insufficient evidence to recommend a Helicobacter pylori test-and-treat strategy as an initial management approach to functional dyspepsia in Korea, suggesting the need for early endoscopic evaluation. Additional studies are necessary to adjust the cutoff age for implementation of immediate endoscopic evaluation of patients without alarm symptoms. Considering the prevalence of H. pylori infection and the limited efficacy of symptomatic relief after its eradication, further well-qualified studies in Korea are warranted.

Functional Dyspepsia in Review: Pathophysiology and Challenges in the Diagnosis and Management due to Coexisting Gastroesophageal Reflux Disease and Irritable Bowel Syndrome

Functional dyspepsia is a common disorder which imposes significant diagnostic and treatment challenges for patients and physicians. The most recent update of the diagnostic criteria subdivides functional dyspepsia into two subcategories based on the main symptom of epigastric pain or postmeal fullness. As we discuss in this review, several studies have shown significant overlap in symptoms and pathophysiology between functional dyspepsia, irritable bowel syndrome, and the spectrum of reflux disorders. This overlap in symptoms can be informative in helping us to understand the underlying pathophysiology, diagnostic approaches, and treatment strategies. The addition of diagnostic testing such as pH impedance manometry of the distal esophagus to the current common diagnostic tests might be helpful in distinguishing between functional dyspepsia and reflux disease. Importantly, various treatment modalities may be more effective than others if the main symptom is burning rather than pain or postmeal fullness rather than early satiation.

Early life events predispose the onset of childhood functional gastrointestinal disorders

BACKGROUND

Functional gastrointestinal disorders (FGIDs) are common digestive conditions characterized by chronic or recurrent symptoms in the absence of a clearly recognized gastrointestinal etiology. The biopsychosocial model, the most accepted concept explaining chronic pain conditions, proposes that the interplay of multiple factors such as genetic susceptibility, early life experiences, sociocultural issues, and coping mechanisms affect children at different stages of their lives leading to the development of different pain phenotypes and pain behaviors. Early life events including gastrointestinal inflammation, trauma, and stress may result in maladaptive responses that could lead to the development of chronic pain conditions such as FGIDs.

AIMS

In this review, we discuss novel findings from studies regarding the long-term effect of early life events and their relationship with childhood chronic abdominal pain and FGIDs.

METHODS

A bibliographic search of the PubMed database was conducted for articles published over the last 20 years using the keywords: "Functional gastrointestinal disorders", "chronic abdominal pain", "chronic pain", "gastrointestinal inflammation", and "early life events". Forty-three articles were chosen for review.

RESULTS

Based on the current evidence, events that take place early in life predispose children to the development of chronic abdominal pain and FGIDs. Conditions that have been studied include cow's milk protein hypersensitivity, pyloric stenosis, gastrointestinal infections, and Henoch-Schonlein purpura, among others.

CONCLUSIONS

Early events may play an important role in the complex pathogenesis of functional gastrointestinal conditions. Timely intervention may have a critical impact on the prevention of this group of chronic incapacitating conditions.