Multi-Organ Pathogenesis and Therapeutic Strategies for Cystic Fibrosis

Cystic Fibrosis (CF) is the most common lethal autosomal inherited disorder that affects all races and ethnicities in the United States. However, it is mostly predominant in the Caucasian populace accounting for about 80% of all CF cases. CF most severe complication can be referred to as pulmonary bronchiectasis and infections of the airways, nonetheless, the devastating effects of the disease have far-reaching consequences beyond lung damage. CF is a heterogeneous disease that is caused by mutations in Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) gene. The impairment or absence of this gene can affect multiple organs and systems and is characterized not only by chronic lung blockage, infections, and inflammation but also by exocrine gland dysfunction, intestinal obstruction, liver pathology, elevated sweat chloride concentration, and in males, infertility due to the congenital bilateral absence of the vas deferens. To this end, we briefly explore the pathological effects of CF and how CF mediates the destruction of several critical organs in the body and some of the gene therapeutical approaches such as gene editing and viral-based strategies available for the treatment of this multi-organ disease.

Low Level of Cystic Fibrosis Transmembrane Conductance Regulator Is Associated with Human Sperm Autophagy and Vitality

Low sperm motility is one of the main causes of male infertility. Cystic fibrosis transmembrane conductance regulator (CFTR, an anion channel protein) is related to the progressive motility of sperm. CFTR disruptor CFTRinh-172 or forskolin (FSK) in this study were used to treat human sperm separately, and the rates of sperm autophagy and progressive motility, mitochondrial membrane potential (MMP) and ATP concentration, and the expression levels of related factors were detected to explore their relationship. It was showed that sperms treated with CFTRinh-172 or FSK reduced the levels of cAMP, CFTR and PKA, but increased sperm autophagy rate, expression levels of AMPK and LC3B. However, reactive oxygen species content had no significant difference. It was indicated that low level of CFTR performed with cAMP and its downstream effectors such as PKA and AMPK to regulate mitochondrial structure and function, leading to increased autophagy rate and reduced vitality of sperm.

c.753＿754delAG, a novel CFTR mutation found in a Chinese patient with cystic fibrosis: A case report and review of the literature

BACKGROUND Cystic fibrosis(CF)is rare in Asian populations relative to the Caucasian population.In this paper,we report the cystic fibrosis transmembrane conductance regulator(CFTR)variation in a family of Chinese CF patients,and systematically review the previous literature.CASE SUMMARY Here we report a 30-month-old Chinese girl who was diagnosed with CF based on her history and symptoms such as recurrent productive cough,wheezing with repeated infection of Pseudomonas aeruginosa,and parasinusitis.Chest computed tomography(CT)scanning revealed obvious exudative lesions and bilateral bronchiectasis.Liver CT scanning revealed a low-density lesion in the left lobe of the liver.A diagnosis of CF was made based upon CFTR gene tests.The CFTR gene was sequenced using the blood samples of her and her parents and showed a heterozygous novel missense mutation of c.753_754delAG in exon 7.In addition,a heterozygous c.1240 C>T mutation was found in exon 10 of the CFTR.The mutation c.753_754delAG was verified to have been inherited from her mother,and the c.1240 C>T mutation was from her father who was diagnosed with congenital absence of vas deferens.CONCLUSION A novel mutation of CFTR,c.753_754delAG,was found in a Chinese CF child.c.2909G>A is the most common mutation among Chinese CF patients.

Characterization of two rat models of cystic fibrosis—KO and F508del CFTR—Generated by Crispr-Cas9

Background: Genetically engineered animals are essential for gaining a proper understanding of the disease mechanisms of cystic fibrosis(CF). The rat is a relevant laboratory model for CF because of its zootechnical capacity, size, and airway characteristics, including the presence of submucosal glands.Methods: We describe the generation of a CF rat model(F508 del) homozygous for the p.Phe508 del mutation in the transmembrane conductance regulator(Cftr) gene. This model was compared to new Cftr-/-rats(CFTR KO). Target organs in CF were examined by histological staining of tissue sections and tooth enamel was quantified by micro-computed tomography. The activity of CFTR was evaluated by nasal potential difference(NPD) and short-circuit current measurements. The effect of VX-809 and VX-770 was analyzed on nasal epithelial primary cell cultures from F508 del rats.Results: Both newborn F508 del and Knock out(KO) animals developed intestinal obstruction that could be partly compensated by special diet combined with an osmotic laxative. The two rat models exhibited CF phenotypic anomalies such as vas deferens agenesis and tooth enamel defects. Histology of the intestine, pancreas, liver, and lungs was normal. Absence of CFTR function in KO rats was confirmed ex vivo by short-circuit current measurements on colon mucosae and in vivo by NPD, whereas residual CFTR activity was observed in F508 del rats. Exposure of F508 del CFTR nasal primary cultures to a combination of VX-809 and VX-770 improved CFTR-mediated Cl-transport.Conclusions: The F508 del rats reproduce the phenotypes observed in CFTR KO animals and represent a novel resource to advance the development of CF therapeutics.

Rare large homozygous CFTR gene deletion in an Iranian patient with cystic fibrosis

Cystic fibrosis, a common autosomal recessive genetic disorder among Caucasians, is caused by defects in the transmembrane conductance regulatory(CFTR) gene. The analysis of CFTR gene mutations is useful to better characterize the disease, and for preconceptional screening, prenatal and preimplantation genetic diagnosis. Here we report the results of a genetic analysis in a 16-year-old boy from southwestern Iran diagnosed as having cystic fibrosis in infancy based on gastrointestinal and pulmonary manifestations, with positive sweat chloride tests. He lacked both normal and mutant forms of the fragment corresponding to the F508 allele in initial genetic studies. Multiplex ligationdependent probe amplification-based testing revealed a homozygous deletion spanning exons 4 to 10 of the CFTR gene. We predict an in-frame deletion removing 373 amino acids based on our sequencing results. Determining CFTR gene mutations in patients and their family members would be helpful to prevent the occurrence of new cases, especially in populations in which consanguinity is common.

"CF chatters": the development of a theoretically informed physical activity intervention for youth with cystic fibrosis

Despite the benefits of physical activity for youth living with cystic fibrosis (CF), the majority of patients are insufficiently active to meet physical activity recommendations. Existing physical activity interventions are atheoretical and tend to prescribe standardized exercise regimes which are often not appealing for children and compromise long term adherence. Following recent calls for counselling based physical activity approaches in the CF population, this study describes the development of a theoretically informed, parent-mediated, behavioural counselling intervention for CF youth―“CF Chatters”. We first a) describe the development of a grounded theory of physical activity in youth with CF;b) explain how this theory informed the development and implementation of the CF Chatters program and c) reflect on the findings of our pilot intervention using a case study research design. CF Chatters participants demonstrated self reported increases in physical activity and quality of life. While further development and more robust objective measures are needed to extend this investigative pilot work, our findings suggest that behavioural counselling is an effective modality for enhancing physical activity participation and quality of life in this life limited group of children and youth.

Pathophysiology of cystic fibrosis and drugs used in associated digestive tract diseases

Cystic fibrosis(CF)causes chronic infections in the respiratory tract and alters the digestive tract.This paper reviews the most important aspects of drug treatment and changes in the digestive tract of patients with CF.This is a review of the literature,emphasizing the discoveries made within the last 15 years by analyzing scientific papers published in journals indexed in the Scientific Electronic Library Online,Sciences Information,United States National Library of Medicine and Medical Literature Analysis and Retrieval System Online databases,both in English and Portuguese,using the key words:cystic fibrosis,medication,therapeutic,absorption,digestion.Randomized,observational,experimental,and epidemiological clinical studies were selected,among others,with statistical significance of 5%.This review evaluates the changes found in the digestive tract of CF patients including pancreatic insufficiency,constipation and liver diseases.Changes in nutritional status are also described.Clinical treatment,nutritional supplementation and drug management were classified in this review as essential to the quality of life of CF patients,and became available through public policies for monitoring and treating CF.The information gathered on CF and a multi professional approach to the disease is essential in the treatment of these patients.

New insights into the pathogenesis of intestina dysfunction:secretory diarrhea and cystic fibrosis

INTRODUCTIONA major function of the intestinal epithelium is to controlthe amount of fluid entering into and being absorbed fromthe lumen.In healthy conditions,net fluid movementfollows an absorptive vector,although significant secretionalso takes place to subserve digestive function.Thus。

Cystic fibrosis transmembrane conductance regulator chloride channel blockers:Pharmacological,biophysical and physiological relevance

Dysfunction of the cystic fibrosis transmembrane con-ductance regulator(CFTR) chloride channel causes cys-tic fibrosis, while inappropriate activity of this channeloccurs in secretory diarrhea and polycystic kidney dis-ease. Drugs that interact directly with CFTR are there-fore of interest in the treatment of a number of diseasestates. This review focuses on one class of small mol-ecules that interacts directly with CFTR, namely inhibi-tors that act by directly blocking chloride movementthrough the open channel pore. In theory such com-pounds could be of use in the treatment of diarrheaand polycystic kidney disease, however in practice allknown substances acting by this mechanism to inhibitCFTR function lack either the potency or specificity forin vivo use. Nevertheless, this theoretical pharmaco-logical usefulness set the scene for the developmentof more potent, specific CFTR inhibitors. Biophysically,open channel blockers have proven most useful as ex-perimental probes of the structure and function of theCFTR chloride channel pore. Most importantly, the useof these blockers has been fundamental in developing afunctional model of the pore that includes a wide innervestibule that uses positively charged amino acid sidechains to attract both permeant and blocking anionsfrom the cell cytoplasm. CFTR channels are also subjectto this kind of blocking action by endogenous anionspresent in the cell cytoplasm, and recently this blocking effect has been suggested to play a role in the physio-logical control of CFTR channel function, in particular as a novel mechanism linking CFTR function dynamically to the composition of epithelial cell secretions. It has also been suggested that future drugs could target this same pathway as a way of pharmacologically increasing CFTR activity in cystic fibrosis. Studying open channel blockers and their mechanisms of action has resulted in significant advances in our understanding of CFTR as a pharmacological target in disease states, of CFTR chan-nel structure and function, and of how CFTR activity is controlled by its local environment.

Cystic fibrosis transmembrane conductance regulator functional evaluations in a G542X+/-IVS8Tn:T7/9 patient with acute recurrent pancreatitis

BACKGROUND Acute recurrent pancreatitis(ARP)is characterized by episodes of acute pancreatitis in an otherwise normal gland.When no cause of ARP is identifiable,the diagnosis of"idiopathic"ARP is given.Mutations in the cystic fibrosis transmembrane conductance regulator(CFTR)gene increase the risk of ARP by 3-to 4-times compared to the general population,while cystic fibrosis(CF)patients present with a 40-to 80-times higher risk of developing pancreatitis.CASE SUMMARY In non-classical CF or CFTR-related disorders,CFTR functional tests can help to ensure a proper diagnosis.We applied an individualized combination of standardized and new CFTR functional bioassays for a patient referred to the Verona CF Center for evaluation after several episodes of acute pancreatitis.The CFTR genotype was G542X+/-with IVS8Tn:T7/9 polymorphism.The sweat(Cl-)values were borderline.Intestinal current measurements were performed according to the European Cystic Fibrosis Society Standardized Operating Procedure.Recent nasal surgery for deviated septum did not allow for nasal potential difference measurements.Lung function and sputum cultures were normal;azoospermia was excluded.Pancreas divisum was excluded by imaging but hypoplasia of the left hepatic lobe was detected.Innovative tests applied in this case include sweat rate measurement by image analysis,CFTR function in monocytes evaluated using a membrane potential-sensitive fluorescent probe,and the intestinal organoids forskolin-induced swelling assay.CONCLUSION Combination of innovative CFTR functional assays might support a controversial diagnosis when CFTR-related disorders and/or non-classical CF are suspected.

Dictamine Stimulates Cystic Fibrosis Transmembrane Conductance Regulator Cl-Transport

Dictamine is a furoquinoline alkaloid isolated from Dictamus dasycarpus Turcz.In the present study,we found that dictamine is able to stimulate the chloride transport activity of wild-type and ΔF508 mutant CFTR.The activity is cAMP-dependent and can be completely reversed by specific CFTR inhibitor CFTRinh-172.In addition,dictamine can further increase the chloride transport activity when CFTR is maximally activated by the combination of cAMP stimulators forskolin（FSK）and IBMX,suggesting direct interaction of dictamine with CFTR.Dictamine may be useful for probing CFTR channel gating mechanisms and used as a lead compound to develop the pharmacological therapy of CFTR-related diseases such as idiopathic chronic pancreatitis and keratoconjunctivitis sicca and cystic fibrosis.

Risk factors for hepatic steatosis in adults with cystic fibrosis: Similarities to non-alcoholic fatty liver disease

AIM To investigate the clinical, biochemical and imaging characteristics of adult cystic fibrosis(CF) patients with hepatic steatosis as compared to normal CF controls.METHODS We performed a retrospective review of adult CF patients in an academic outpatient setting during 2016. Baseline characteristics, genetic mutation analysis as well as laboratory values were collected. Abdominal imaging(ultrasound, computed tomography, magnetic resonance) was used to determine presence of hepatic steatosis. We compare patients with hepatic steatosis to normal controls.RESULTS Data was collected on 114 patients meeting inclusion criteria. Seventeen patients(14.9%) were found to have hepatic steatosis on imaging. Being overweight(BMI > 25)(P = 0.019) and having a higher pp FEV1(75 vs 53, P = 0.037) were significantly associated with hepatic steatosis. Patients with hepatic steatosis had a significantly higher median alanine aminotransferase level(27 vs 19, P = 0.048). None of the hepatic steatosis patients had frank CF liver disease, cirrhosis or portal hypertension. We found no significant association with pancreatic insufficiency or CF related diabetes.CONCLUSION Hepatic steatosis appears to be a clinically and phenotypically distinct entity from CF liver disease. The lack of association with malnourishment and the significant association with higher BMI and higher pp FEV1 demonstrate similarities with non-alcoholic fatty liver disease. Long term prospective studies are needed to ascertain whether CF hepatic steatosis progresses to fibrosis and cirrhosis.

Lumacaftor/ivacaftor therapy is associated with reduced hepatic steatosis in cystic fibrosis patients

BACKGROUND Hepatic steatosis is a common form of cystic fibrosis associated liver disease(CFLD)seen in an estimated 15%-60%of patients with cystic fibrosis(CF).The pathophysiology and health implications of hepatic steatosis in cystic fibrosis remain largely unknown.In the general population,hepatic steatosis is strongly associated with insulin resistance and type 2 diabetes.Cystic fibrosis related diabetes(CFRD)impacts 40%-50%of CF adults and is characterized by both insulin insufficiency and insulin resistance.We hypothesized that patients with CFRD would have higher levels of hepatic steatosis than cystic fibrosis patients without diabetes.AIM To determine whether CFRD is associated with hepatic steatosis and to explore the impact of lumacaftor/ivacaftor therapy on hepatic steatosis in CF.METHODS Thirty patients with CF were recruited from a tertiary care medical center for this cross-sectional study.Only pancreatic insufficient patients with CFRD or normal glucose tolerance(NGT)were included.Patients with established CFLD,end stage lung disease,or persistently elevated liver enzymes were excluded.Mean magnetic resonance imaging(MRI)proton density fat fraction(PDFF)was obtained for all participants.Clinical characteristics[age,sex,body mass index,percent predicted forced expiratory volume at 1 s(FEV1),lumacaftor/ivacaftor use]and blood chemistries were assessed for possible association with hepatic steatosis.Hepatic steatosis was defined as a mean MRI PDFF>5%.Patients were grouped by diabetes status(CFRD,NGT)and cystic fibrosis transmembrane conductance regulator(CFTR)modulator use(lumacaftor/ivacaftor,no lumacaftor/ivacaftor)to determine between group differences.Continuous variables were analyzed with a Wilcoxon rank sum test and discrete variables with a Chi square test or Fisher’s exact test.RESULTS Twenty subjects were included in the final analysis.The median age was 22.3 years(11.3-39.0)and median FEV1 was 77%(33%-105%).Twelve subjects had CFRD and 8 had NGT.Nine subjects were receiving lumacaftor/ivacaftor.The median PDFF was 3.0%(0.0%-21.0%).Six subjects(30%)had hepatic steatosis defined as PDFF>5%.Hepatic fat fraction was significantly lower in patients receiving lumacaftor/ivacaftor(median,range)(2.0%,0.0%-6.4%)than in patients not receiving lumacaftor/ivacaftor(4.1%,2.7-21.0%),P=0.002.Though patients with CFRD had lower PDFF(2.2%,0.0%-14.5%)than patients with NGT(4.9%,2.4-21.0%)this did not reach statistical significance,P=0.06.No other clinical characteristic was strongly associated with hepatic steatosis.CONCLUSION Use of the CFTR modulator lumacaftor/ivacaftor was associated with significantly lower hepatic steatosis.No association between CFRD and hepatic steatosis was found in this cohort.

A review of cystic fibrosis:Basic and clinical aspects

Cystic fibrosis is an autosomal recessive disease caused by mutations of the gene encoding the cystic fibrosis transmembrane conductance regulator(CFTR).Here we summarize,at the basic descriptive level,clinical and genetic characteristics of cystic fibrosis gene mutations,while emphasizing differences between CF mutations found in Chinese pediatric CF patients compared to those found in Caucasian CF patients.In addition,we describe animal models used to study human cystic fibrosis disease and highlight unique features of each model that mimic specific human CF-associated signs and symptoms.At the clinical level,we summarize CF clinical manifestations and diagnostic,treatment,and prognostic methods to provide clinicians with infor-mation toward reducing CF misdiagnosis and missed diagnosis rates.

Emerging role of cystic fibrosis transmembrane conductance regulator- an epithelial chloride channel in gastrointestinal cancers

Cystic fibrosis transmembrane conductance regulator(CFTR), a glycoprotein with 1480 amino acids, has been well established as a chloride channel mainly expressed in the epithelial cells of various tissues and organs such as lungs, sweat glands, gastrointestinal system, and reproductive organs. Although defective CFTR leads to cystic fibrosis, a common genetic disorder in the Caucasian population, there is accumulating evidence that suggests a novel role of CFTR in various cancers, especially in gastroenterological cancers, such as pancreatic cancer and colon cancer. In this review, we summarize the emerging findings that link CFTR with various cancers, with focus on the association between CFTR defects and gastrointestinal cancers as well as the underlying mechanisms. Further study of CFTR in cancer biology may help pave a new way for the diagnosis and treatment of gastrointestinal cancers.

Cystic fibrosis associated liver disease in children

Cystic fibrosis(CF)is an autosomal recessive disorder caused by mutations in the CF transmembrane conductance regulator gene.CF liver disease develops in 5%-10%of patients with CF and is the third leading cause of death among patients with CF after pulmonary disease or lung transplant complications.We review the pathogenesis,clinical presentations,complications,diagnostic evaluation,effect of medical therapies especially CF transmembrane conductance regulator modulators and liver transplantation in CF associated liver disease.

Tetramethylpyrazine stimulates cystic fibrosis transmembrane conductance regulator-mediated anion secretion in distal colon of rodents

AIM： To investigate the effect of tetramethylpyrazine （TMP）, an active compound from Ligustium Wollichii Franchat, on electrolyte transport across the distal colon of rodents and the mechanism involved.METHODS： The short-circuit current （Isc） technique in conjunction with pharmacological agents and specific inhibitors were used in analyzing the electrolyte transport across the distal colon of rodents. The underlying cellular signaling mechanism was investigated by radioimmunoassay analysis （RIA） and a special mouse model of cystic fibrosis.RESULTS： IMP stimulated a conoentration-dependent rise in ISCl, which was dependent on both Cl^- and HCO3^-, and inhibited by apical application of diphenylamine-2,2＇-dicarboxylic acid （DPC） and glibenclamide, but resistant to 4,4＇-diisothiocyanatostilbene-2,2＇-disulfonic acid disodium salt hydrate （DIDS）. Removal of Na^＋ from basolateral solution almost completely abolished the Isc response to TMP, but it was insensitive to apical Na^＋ replacement or apical Na^＋ channel blocker, amiloride. Pretreatment of colonic mucosa with BAPTA-AM, a membrane-permeable selective Ca2＋ chelator, did not significantly alter the TMP-induced Iso No additive effect of forskolin and 3-isobutyl-l-methylxanthine （[BMX） was observed on the TMP-induced Isc, but it was significantly reduced by a protein kinase A inhibitor, H89.RIA results showed that TMP （1 mmol/L） elicited a significant increase in cellular cAMP production, which was similar to that elicited by the adenylate cyclase activator, forskolin （10μmol/L）. The TMP-elicited Isc as well as forskolin- or IBMX-induced Isc were abolished in mice with homozygous mutation of the cystic fibrosis transmembrane conductance regulator （CFTR） presenting defective CFTR functions and secretions.CONCLUSION： TMP may stimulate cAMP-dependent and CFTR-mediated Cl^- and HCO3^- secretion. This may have implications in the future development of alternative treatment for constipation.

Cystic fibrosis transmembrane conductance regulator prevents ischemia/reperfusion induced intestinal apoptosis via inhibiting PI3K/AKT/NF-κB pathway

BACKGROUND Intestinal ischemia/reperfusion(I/R)injury is a fatal syndrome that occurs under many clinical scenarios.The apoptosis of intestinal cells caused by ischemia can cause cell damage and provoke systemic dysfunction during reperfusion.However,the mechanism of I/R-induced apoptosis remains unclear.Cystic fibrosis transmembrane conductance regulator(CFTR)is a cAMP-activated chloride channel.Few researchers have paid attention to its role in intestinal I/R injury,or the relationship between CFTR and intestinal apoptosis induced by hypoxia/reoxygenation(H/R).AIM To investigate the effects of CFTR on I/R-induced intestinal apoptosis and its underlying molecular mechanisms.METHODS An intestinal I/R injury model was established in mice with superior mesenteric artery occlusion, and Caco2 cells were subjected to H/R for the simulation of I/R in vivo.RESULTSThe results suggested that CFTR overexpression significantly increased the Caco2 cell viability anddecreased cell apoptosis induced by the H/R. Interestingly, we found that the translocation of p65,an NF-κB member, from the cytoplasm to the nucleus after H/R treatment can be reversed by theoverexpression of CFTR, the NF-κB P65 would return from the nucleus to the cytoplasm asdetermined by immunostaining. We also discovered that CFTR inhibited cell apoptosis in theH/R-treated cells, and this effect was significantly curbed by the NF-κB activator BA, AKTinhibitor GSK690693 and the PI3K inhibitor LY294002. Moreover, we demonstrated that CFTRoverexpression could reverse the decreased PI3K/AKT expression induced by the I/R treatment invivo or H/R treatment in vitro.CONCLUSIONThe results of the present study indicate that the overexpression of CFTR protects Caco2 cells fromH/R-induced apoptosis;furthermore, it also inhibits H/R-induced apoptosis through thePI3K/AKT/NF-κB signaling pathway in H/R-treated Caco2 cells and intestinal tissues.

Applications of lung clearance index in monitoring children with cystic fibrosis

A sensitive, reproducible and feasible measure of lung function for monitoring the respiratory health is a prerequisite for the optimization of management of the patients with cystic fibrosis(CF). Spirometry has been considered the method of choice, although it is applicable only in children older than 6 years of age, as good cooperation is necessary for its proper performance. However, over the last15 years, scientific interest in gas dilution techniques and particularly in multiple breath wash out(MBW) method has been revived. The most commonly reported index of MBW is lung clearance index(LCI). The aim of this review is to present the most recent developments in the application of LCI as a monitoring index of respiratory status of CF patients. LCI is a sensitive and reproducible marker of ventilation inhomogeneity. It is more sensitive than spirometry and, unlike spirometry; it can be performed across the whole pediatric age range. Since it is dependent on body size, until at least the age of 6 years, the relative and not the absolute changes are more appropriate for providing clinically meaningful conclusion on ventilation inhomogeneity. Until now, MBW has been mainly used as a research tool. Based on the currently available data LCI cannot safely predict high-resolution computed tomography findings in children with CF, especially in infants. It can be used as an end-point measure for the assessment of beneficial effect of interventions. However, its utility as an outcome measure for the efficacy of therapeutic interventions seems to be dependent on the pathophysiologic mechanisms that underlie each intervention. It seems that more studies,especially longitudinal ones, are required in order to fully clarify the clinical usefulness of LCI, not only in the research setting, but also in every day practice of CF clinic.

Screening strategy for gastrointestinal and hepatopancreatobiliary cancers in cystic fibrosis

Based on systematic review and meta-analysis,the risk for developing cancers in patients with cystic fibrosis(CF)is known to be significantly greater than in the general population,including site-specific cancers of the esophagus,small bowel,colon,liver,biliary tract,and pancreas.An even higher risk has been found in patients who have severe CF transmembrane conductance regulator(CFTR)genotypes or who have undergone organ transplantation and are immunosuppressed.The risk continues to rise as life expectancies steadily climb due to advancements in medical care and treatment for CF.The colorectal cancer risk is at such a high level that CF has now been declared a hereditary colon cancer syndrome by the Cystic Fibrosis Foundation.The CFTR gene has been stronglyassociated with the development of gastrointestinal(GI)cancers and mortality in the CF population.Even CF carriers have shown an increased rate of GI cancers compared to the general population.Several limitations exist with the reported guidelines for screening of GI and hepatopancreatobiliary cancers in the CF population,which are largely universal and are still emerging.There is a need for more precise screening based on specific risk factors,including CFTR mutation,medical co-morbidities(such as gastroesophageal reflux disease,distal intestinal obstruction syndrome,and diabetes mellitus),familial risks for each cancer,gender,age,and other factors.In this review,we propose changes to the guidelines for GI screening of patients with CF.With the development of CFTR modulators,additional studies are necessary to elucidate if there is an effect on cancer risk.