Polymorphism of cystic fibrosis gene in Japanese patients with chronic pancreatitis

Comparison of idiopathic recurrent acute pancreatitis [IRAP] and recurrent acute pancreatitis with genetic mutations

BACKGROUND

Idiopathic recurrent acute pancreatitis (IRAP) describes frequent episodes of pancreatitis without an etiology found using current testing. We compared the natural history of IRAP with recurrent acute pancreatitis with genetic mutations.

METHODS

Retrospective cohort of patients with recurrent acute pancreatitis (≥2 episodes) and negative conventional testing. All patients had ≥1 episode after cholecystectomy and completed genetic testing. Primary outcomes were chronic pancreatitis incidence, pancreatic cancer, and mortality. Secondary outcomes included opioid and ERCP utilization.

RESULTS

128 patients met criteria for presumed IRAP. 35 patients met criteria for true IRAP. 12 patients had recurrent acute pancreatitis with gene mutations. Chronic pancreatitis developed in 27 (77.1%) IRAP patients over a median of 6 years. Chronic pancreatitis incidence was similar in IRAP and CFTR mutation carriers; but developed later in SPINK1 carriers. No patients developed pancreatic cancer or died from pancreatic-related causes. Patients were frequently treated with oral opioids and ERCP, without significant differences within or between groups.

CONCLUSION

IRAP and pancreatitis in mutation carriers is associated with chronic pancreatitis. Important differences in natural history were observed, but no association was found with cancer or pancreas-related mortality. Efforts to understand the genetic contributions to IRAP, minimize opioids and unnecessary ERCPs are encouraged.

Novel mutation c.1210-3C > G in cis with a poly-T tract of 5T affects CFTR mRNA splicing in a Chinese patient with cystic fibrosis

Cystic fibrosis (CF) is a rare autosomal recessive disease with only one pathogenic gene cystic fibrosis transmembrane conductance regulator (CFTR). To identify the potential pathogenic mutations in a Chinese patient with CF, we conducted Sanger sequencing on the genomic DNA of the patient and his parents and detected all 27 coding exons of CFTR and their flanking intronic regions. The patient is a compound heterozygote of c.2909G > A, p.Gly970Asp in exon 18 and c.1210-3C > G in cis with a poly-T of 5T (T5) sequence, 3 bp upstream in intron 9. The splicing effect of c.1210-3C > G was verified via minigene assay in vitro, indicating that wild-type plasmid containing c.1210-3C together with T7 sequence produced a normal transcript and partial exon 10-skipping-transcript, whereas mutant plasmid containing c.1210-3G in cis with T5 sequence caused almost all mRNA to skip exon 10. Overall, c.1210-3C > G, the newly identified pathogenic mutation in our patient, in combination with T5 sequence in cis, affects the CFTR gene splicing and produces nearly no normal transcript in vitro. Moreover, this patient carries a p.Gly970Asp mutation, thus confirming the high-frequency of this mutation in Chinese patients with CF.

IVS8-5T Allele of CFTR is the Risk Factor in Chronic Pancreatitis, Especially in Idiopathic Chronic Pancreatitis

BACKGROUND

Cystic fibrosis transmembrane conductance regulator IVS8-5T gene variation appears to be associated with a higher risk of chronic pancreatitis (CP); however, there is inconsistency between previous reported studies. Here, we performed a meta-analysis to investigate this relationship.

MATERIALS AND METHODS

PubMed and WANFANG databases were searched for the case-control studies that contained Patients with CP with IVS8-5T variation. Odd ratios (ORs) and 95% confidence intervals (CIs) were calculated to assess the relevance of IVS8-5T gene variation and CP.

RESULTS

Analysis showed that the frequency of the 5T allele was significantly higher in CP subjects than that in control subjects (OR = 1.43, 95% CI: 1.13-1.81, I² = 1.2%). Based on the subgroup analysis stratified by etiology, the 5T allele was associated with a higher risk of idiopathic chronic pancreatitis (ICP) (OR = 1.80, 95% CI: 1.18-2.76, I² = 0.0%) and not alcoholic CP (OR = 2.14, 95% CI: 0.98-4.66, I² = 0.0%). Further study indicated that the 5T allele was related to higher ICP prevalence in the European population (OR = 1.79, 95% CI: 1.06-3.03, I² = 0.0%). In contrast, there was no significant difference between ICP subjects and healthy controls within the Asian population (OR = 1.84, 95% CI: 0.91-3.72, I² = 38.0%).

CONCLUSIONS

Cystic fibrosis transmembrane conductance regulator IVS8-5T is a risk factor in patients with CP. IVS8-5T variation may play a significant role in the occurrence of ICP, especially in the European population.

Functional characteristics of L1156F-CFTR associated with alcoholic chronic pancreatitis in Japanese

Although cystic fibrosis is rare in Japanese, measurement of sweat Cl(-) has suggested mild dysfunction of cystic fibrosis transmembrane conductance regulator (CFTR) in some patients with chronic pancreatitis. In the present study, we have investigated the association of CFTR variants and chronic pancreatitis in Japanese and the functional characteristics of a Japanese- and pancreatitis-specific CFTR variant, L1156F. Seventy patients with alcoholic chronic pancreatitis, 18 patients with idiopathic chronic pancreatitis, and 180 normal subjects participated. All exons and their boundaries and promoter region of the CFTR gene were sequenced. Human embryonic kidney-293 cells were transfected with three CFTR variants (M470V, L1156F, and M470V+L1156F), and the protein expression was examined. Xenopus laevis oocytes were injected with the CFTR variants, and bicarbonate (HCO3 (-)) transport activity was examined. CFPAC-1 cells were transfected with the CFTR variants and Cl(-)/HCO3 (-) exchange activity was examined. Six variants (E217G, I556V, M470V, L1156F, Q1352H, and R1453W) were identified in the coding region of the CFTR gene. Cystic fibrosis-causing mutations were not found. The allele frequencies of L1156F and Q1352H in alcoholic chronic pancreatitis (5.0 and 7.9%) were significantly (P < 0.01) higher than those in normal subjects (0.6 and 1.9%). L1156F was linked with a worldwide CFTR variant, M470V. Combination of M470V and L1156F significantly reduced CFTR expression to ∼60%, impaired CFTR-mediated HCO3 (-)/Cl(-) transport activity to 50-60%, and impaired CFTR-coupled Cl(-)/HCO3 (-) exchange activity to 20-30%. The data suggest that the Japanese-specific CFTR variant L1156F causes mild dysfunction of CFTR and increases the risk of alcoholic chronic pancreatitis in Japanese.

Genetic risk for alcoholic chronic pancreatitis

In recent years many studies have examined the genetic predisposition to pancreatic diseases. Pancreatic disease of an alcoholic etiology was determined to be a multi-factorial disease, where environmental factors interact with the genetic profile of the individual. In this review we discuss the main results from studies examining the frequency of genetic mutations in alcoholic chronic pancreatitis.

CFTR gene mutation in patients with apparently idiopathic pancreatitis: lack of phenotype-genotype correlation

BACKGROUND AND AIMS

Despite an extensive search, no cause is found for recurrent acute/chronic pancreatitis (idiopathic pancreatitis (IP)) in about 20% of patients. In these patients, CFTR gene mutations may be identified. The aims of this study were (1) to describe the natural history of pancreatitis associated with the CFTR mutation, (2) to look for genotype-phenotype correlations, and (3) to examine the frequency of CFTR mutations in a population of patients with IP.

RESULTS

100 consecutive patients with IP were included between 1998 and 2005. 50% had one of the 33 most frequent CFTR gene mutations (common CF mutations, uncommon mutations causing variable phenotypes and variants of unknown significance in 28, 44 and 28%, respectively). Patients with a CFTR gene mutation were significantly younger than those without (34 vs. 40 years, p = 0.03). Duration of follow-up (3.5 vs. 3 years), proportion of patients with acute pancreatitis as first symptom (76 vs. 74%) were not significantly different. Signs of chronic pancreatitis (ductal changes and pancreatic calcifications), pseudocysts, common bile duct stenosis, exocrine or endocrine insufficiency occurred in 36, 26, 4, 10 and 12% of patients with CFTR gene mutations respectively, which was not different from patients without mutations. No phenotype-genotype correlation was observed.

CONCLUSIONS

In patients with IP, clinical and radiological manifestations are not related to the presence of a CFTR gene mutation or to the type of mutation.

CFTR polymorphisms in patients with alcoholic chronic pancreatitis

INTRODUCTION

Pancreas susceptibility to alcohol is variable and only 5-10% of chronic alcohol abusers develop chronic pancreatitis; the role of genetic factors in this process is unknown. The CFTR gene encodes a protein that acts on epithelial cells and plays a key role in normal exocrine pancreatic function.

METHODS

This study investigated the frequency of polymorphisms in intron 8 of the CFTR gene in patients with alcoholic chronic pancreatitis. Three groups of patients were studied: group A - 68 adult alcoholics with a diagnosis of chronic pancreatitis; group B - 68 adult alcoholics without pancreatic disease or liver cirrhosis and group C - 104 healthy nonalcoholic adults.

RESULTS

T5/T7 genotype was more frequent in group A (11.8%) than in group B (2.9%) (p = 0.0481), and there was no statistical difference when groups A and C (5.8%) were compared (p = 0.1317). The haplotype combination (TG)10-T7/(TG)11-T7 was more frequent in groups B (23.5%) and C (20.2%) than in group A (7.3%) (p = 0.0080 and 0.0162).

CONCLUSION

There are differences when these three groups are compared and individuals with T5/T7 genotype might have a greater risk of developing chronic pancreatitis when they become chronic alcoholics.

Comparative analysis of common CFTR polymorphisms poly-T, TG-repeats and M470V in a healthy Chinese population

AIM: To investigate the three important cystic fibrosis transmembrane conductance regulator (CFTR) haplotypes poly-T, TG-repeats and the M470V polymorphisms in the Chinese population, and to compare their distribution with that in Caucasians and other Asian populations.

METHODS: Genomic DNA was extracted from blood leukocytes. Exons 9 and 10 of the CFTR gene were obtained through polymerase chain reaction (PCR). Exon 9 DNA sequences were directly detected by an automated sequencer and poly-T and TG-repeats were identified by direct sequence analysis. Pure exon 10 PCR-amplified products were digested by HphI restriction enzyme and the M470V mutation was detected by the AGE photos of digestion products.

RESULTS: T7 was the most common (93.6%) haplotype and the (TG)11 frequency of 57.2% and (TG)12 frequency of 40.9% were dominant haplotypes in the junction of intron 8 (IVS-8) and exon 9. The frequency of T5 was 3.8% and all T5 allele tracts (10 alleles) were joined with (TG)12. Four new alleles of T6 (1.5%) were found in three healthy individuals. In exon 10, the V allele (56.1%) was slightly more frequent than the M allele (43.9%), and the M/V (45.5%) was the dominant genotype in these individuals. The three major haplotypes T7-(TG)11-V470, T7-(TG)12-M470 and T7-TG11-M470 were related to nearly 86.0% of the population.

CONCLUSION: The polymorphisms of poly-T, TG-repeats, and M470V distribution were similar to those in other East Asians, but they had marked differences in frequency from those single haplotype polymorphisms or linkage haplotypes in Caucasians. Thus, they may be able to explain the low incidence of CF and CF-like diseases in Asians.

Mutation analysis of SPINK1 and CFTR gene in Korean patients with alcoholic chronic pancreatitis

Several genetic mutations have been reported to increase susceptibility to chronic pancreatitis. However, their roles in alcoholic chronic pancreatitis are controversial. We investigated the prevalence of SPINK1 N34S and new CFTR Q1352H mutations in alcoholic chronic pancreatitis in Korea. Forty-three patients with alcoholic chronic pancreatitis were enrolled and 35 healthy individuals served as controls. The SPINK1 N34S mutation was detected by the PCR-RFLP technique. The CFTR Q1352H mutation was examined with PCR direct sequencing. Mean age of chronic pancreatitis and control groups was 53.2 and 51.3 years, respectively. A SPINK1 N34S was detected as a heterozygote in one (2.4%) patient with alcoholic chronic pancreatitis and a heterozygote CFTR Q1352H was detected in one other patient. In the control population, neither SPINK1 nor CFTR mutation was detected. This study shows that SPINK1 N34S and CFTR Q1352H mutations are uncommon and do not play an important role in chronic alcoholic pancreatitis in Korea.

Certain background factors exhibit an association with an increased risk for pancreatic calcification among Japanese male alcoholics

OBJECTIVE

This was a cross-sectional study conducted from April 2003 through March 2004 to investigate the background factors related to pancreatic calcification (PC) in male Japanese alcoholics.

METHODS AND RESULTS

Helical computed tomography examination revealed PC in 44 of 263 alcoholics, and this group was further divisible into 3 subgroups: "scant" (n = 24), "moderate" (n = 6), and "extensive" PC subgroups (n = 14). The extensive subgroup was associated with larger daily ethanol consumption (P = 0.05) and high-alcohol beverages, such as whisky (P = 0.02). The moderate subgroup was associated with a longer duration of habitual drinking (P = 0.04), whereas the scant PC group was associated with never having smoked (P = 0.05) and with low-alcohol beverages, such as beer (P = 0.09). None of the 40 subjects with inactive mitochondrial aldehyde dehydrogenase (ALDH2*2 allele) exhibited PC (P = 0.004). Heterozygous alcohol dehydrogenase 2 genotype (ADH2*1/2*2) exhibited an association with the scant subgroup (P = 0.02). The TG12 repeats in the cystic fibrosis transmembrane conductance regulator (CFTR) gene tended to have a weak association with PC.

CONCLUSION

Drinking behavior, smoking status, and genetic backgrounds are associated with PC and are likely to increase the risk for alcoholic chronic pancreatitis.

Homozygous (TG)11 allele in intron 8 of the cystic fibrosis transmembrane conductance regulator (CFTR) gene has a protective role against bicarbonate decrease in pure pancreatic juice among Japanese male alcoholics

BACKGROUND

Heavy drinkers have a high incidence of chronic pancreatitis (CP), but the mechanism of alcohol-related CP is largely unknown. Exocrine pancreatic insufficiency exists in about 90% of the patients with cystic fibrosis (CF), which results from an abnormal cystic fibrosis transmembrane conductance regulator gene (CFTR).

AIM

To investigate in Japanese alcoholics the association between bicarbonate concentration in pure pancreatic juice and one of the polymorphisms of the CFTR gene, the (TG)m Tn tract length in intron 8.

METHODS

Fifty-six patients under treatment for alcohol dependence were stimulated by intravenous injection of secretin during endoscopic retrograde cholangiopancreatography to provide pancreatic juice specimens. Individual maximum bicarbonate concentrations (MBC) were compared with (TG)m Tn tract polymorphisms identified by directly sequencing lymphocyte DNA.

RESULTS

Among the 41 patients able to provide adequate pancreatic juice specimens, 15 had low MBC and 26 had normal MBC. The frequencies of the six haplotypes identified in these patients were 17.1% (TG)11T7/(TG)llT7, 46.3% (TG)11T7/(TG)12T7, 29.3% (TG)12T7/(TG)12T7, 2.4% (TG)10T9/(TG)11T7, 2.4% (TG)12T5/(TG)11T7, and 2.4% (TG)12T6/(TG)12T7. Among the 92.7% of patients who had the common (TG) miT7/(TG)m2T7 haplotype, all of the 7 with homozygous (TG)11 alleles had normal MBC (p<0.05).

CONCLUSION

Alcoholics with homozygous (TG)11 alleles in intron 8 of the CFTR gene appear to be protected against decreased MBC, compared with those who have the (TG)11/(TG)12 and (TG)12/(TG)12 genotypes, suggesting a role for CFTR gene polymorphism in the progression of alcohol-related pancreatic disease.

Risk of pancreatitis with mutation of the cystic fibrosis gene

BACKGROUND

Between 5% and 15% of patients with recurrent pancreatitis have no identified etiology after routine investigation and advanced endoscopic evaluation.

OBJECTIVE

To determine whether mutation of the cystic fibrosis transmembrane conductance regulator (CFTR) gene is a risk factor for idiopathic pancreatitis.

METHODS

We compared the frequency of CFTR mutations as measured by DNA probe analysis in a case group of persons with idiopathic pancreatitis and a control group without pancreatitis, all of whom underwent endoscopic retrograde cholangiopancreatography. A separate analysis compared the prevalence of CFTR mutations between the case group and controls with pancreatitis of known etiology. A subgroup comparison was made between cases of pancreas divisum with pancreatitis and controls with pancreas divisum and no pancreatitis.

RESULTS

CFTR mutations were present in 19 (19%) of 96 cases and 7 (3.5%) of 198 controls without pancreatitis (odds ratio, OR = 6.7; 95% CI, 2.8-16.3; p < 0.00001). Compared to the controls with a known cause of pancreatitis (N = 78), cases had a higher prevalence of CFTR mutations (19% vs 2.6%, OR = 9.4; CI, 2.1-41.7; p= 0.0005). Among subjects with pancreas divisum, CFTR mutations were present in 8 (22%) of 37 cases compared to 0 (0%) of 20 controls (OR = 11.8; CI, 8.9-14.7; p= 0.02).

CONCLUSION

The risk of idiopathic pancreatitis is greater among persons with CFTR mutations as compared to persons without CFTR mutations. Among persons with pancreas divisum, CFTR mutations appear to increase the risk for pancreatitis.

A finger sweat chloride test for the detection of a high-risk group of chronic pancreatitis

OBJECTIVES

Mutations of the cystic fibrosis transmembrane conductance regulator (CFTR) gene are associated with chronic pancreatitis in Caucasians. We developed a simple method for measuring finger sweat chloride concentration to test whether CFTR dysfunction underlies chronic pancreatitis in Japan where cystic fibrosis (CF) is rare.

METHODS

We studied 25 patients with chronic (21 alcoholic and 4 idiopathic) pancreatitis and 25 healthy volunteers. Sweat chloride concentrations were measured by a finger sweat chloride test. We analyzed DNA for 20 common CFTR mutations in Europeans, 9 CF-causing mutations in Japanese, and 2 polymorphic loci, a poly-T tract and (TG) repeats, at intron 8.

RESULTS

Thirteen patients (52%) had sweat chloride levels >60 mmol/L, a level consistent with CF, while only 4 (16%) healthy subjects exceeded this level. The 29 CF mutations and the 5T allele were detected in neither the patients nor controls. The (TG) 12 allele was common in both the patients (58%) and controls (48%). The (TG) 12/12 genotype was common in alcoholic pancreatitis (29%) compared with the (TG) 11/11 (10%). Patients with the (TG) 12/12 genotype had significantly higher sweat chloride concentrations than the controls.

CONCLUSION

CFTR dysfunction as evidenced by a finger sweat chloride test is present in about half of Japanese patients with chronic pancreatitis, suggesting that this test may be useful for detecting the high-risk group. A higher proportion of the (TG) 12 allele may be a genetic background for elevated sweat chloride concentrations in Japanese patients.

Mutations of the CFTR gene in pancreatic disease

INTRODUCTION

An association has been found between CFTR gene mutations and chronic pancreatitis; however, there is a lack of information about the frequency of CFTR gene mutations in acute pancreatitis and in pancreatic cancer.

AIM

To prospectively evaluate the prevalence of CFTR gene mutations in acute pancreatitis, chronic pancreatitis, and pancreatic cancer.

METHODOLOGY

Ninety-eight consecutive patients were studied and divided into 3 groups: 34 patients with acute pancreatitis, 46 patients with chronic pancreatitis, and 18 patients with pancreatic cancer. The mutation analysis of the CFTR gene was carried out using diagnostic commercial kits for the simultaneous detection of 29 mutations and Tn polymorphism.

RESULTS

Among the 98 patients studied, 12 (12.2%) had CFTR gene mutations: 2 of the 34 patients (5.9%) with acute pancreatitis, 9 of the 46 (19.6%) with chronic pancreatitis, and 1 of the 18 (5.6%) with pancreatic cancer. All the mutations were found in heterozygosis (2 DeltaF508, 1 W1282X, and 9 T5 allele).

CONCLUSION

Our prospective study adds further information about the frequency of CFTR mutations in patients with a single episode of acute pancreatitis. Furthermore, our results suggest an association of CFTR gene mutations with chronic alcoholic pancreatitis and emphasize the need for a multicenter study, possibly multinational, to conclusively establish the role of CFTR mutations as a genetic susceptibility factor for this disease.

Cystic fibrosis and related diseases of the pancreas

The discovery of the gene for cystic fibrosis (CF), the cystic fibrosis transmembrane conductance regulator (CFTR), brought about a new era in the study of this disease. Identification of the molecular target has yielded a flood of data that add to our understanding of the pathogenesis, diagnosis and treatment of CF. The CFTR protein is a cAMP-regulated Cl(-) channel with multiple functions in epithelial cells. In the exocrine pancreas the CFTR plays a key role in the apical Cl(-), HCO(3)(-), and water transport in duct cells. The severe loss of functions, caused by mutations of the CFTR gene, leads to pathological lesions of the pancreas. Over 1200 CFTR mutations and polymorphisms have been identified and their diversity may explain the high level of heterogeneity in the CF phenotype. Mutation analyses of the CFTR gene have revealed a spectrum of CFTR-related diseases that do not fit the classical CF picture but are associated with dysfunction of CFTR, such as chronic pancreatitis.

Determination of the relative contribution of three genes-the cystic fibrosis transmembrane conductance regulator gene, the cationic trypsinogen gene, and the pancreatic secretory trypsin inhibitor gene-to the etiology of idiopathic chronic pancreatitis

In the last 5 years, mutations in three genes, the cystic fibrosis transmembrane conductance regulator (CFTR) gene, the cationic trypsinogen (PRSS1) gene, and the pancreatic secretory trypsin inhibitor (PSTI) gene, have been found to be associated with chronic pancreatitis (CP). In this study, using established mutation screening methods, we systematically analysed the entire coding sequences and all exon/intron junctions of the three genes in 39 patients with idiopathic CP (ICP), with a view to evaluating the relative contribution of each gene to the aetiology of the disease. Our results demonstrate that, firstly, 'gain-of-function' mutations in the PRSS1 gene may occasionally be found in an obvious ICP subject. Secondly, presumably 'loss-of-function' mutations in the PSTI gene appear to be frequent, with a detection rate of at least 10% in ICP and, finally, abnormal CFTR alleles are common: at least 20% of patients carried one of the most common CFTR mutations, and about 10% of patients were compound heterozygotes, having at least one 'mild' allele. Thus, in total, about 30% of ICP patients carried at least one abnormal allele in one of the three genes, and this is the most conservative estimate. Moreover, a trans-heterozygous state with sequence variations in the PSTI/CFTR genes was found in three patients. However, an association between the 5T allele in intron 8 of the CFTR gene and ICP remains unproven.