SLC26A9 SNP rs7512462 is not associated with lung disease severity or lung function response to ivacaftor in cystic fibrosis patients with G551D-CFTR

BackgroundThe CFTR modulator ivacaftor has been variably effective in treating individuals with cystic fibrosis (CF) who harbor CFTR gating variants such as G551D, as well as other classes of CFTR variants when used with other modulators. Because CFTR genotype does not fully explain this variability, defining genetic modifiers of response to modulator therapy is of particular interest to the field of individualized CF drug therapy. Previous studies have proposed that a variant in SLC26A9 (rs7512462) is associated with lung disease severity and with response to treatment with ivacaftor in individuals with CF who carry G551D or gating variants.MethodsGiven the implications for CF treatment, we re-examined the reported associations in three cohorts; patients enrolled in the Twin and Siblings study at Johns Hopkins University, the CF modifier study at the University of North Carolina at Chapel Hill, and the prospective G551D Observational (GOAL) study. The GOAL study was specifically designed to measure lung function response to ivacaftor.ResultsWe find no association between SLC26A9 (rs7512462) genotype and lung disease severity (n = 272) or change in lung function at one-, three-, and six-month intervals following ivacaftor treatment(n = 141) in individuals with CF who carry at least one G551D variant.ConclusionsOur inability to replicate this association indicates that rs7512462 genotype should not be used in treatment decisions.     

Penetrance is a critical parameter for assessing the disease liability of CFTR variants

BackgroundMajor issues of newborn screening (NBS) for CF are the assessment of disease liability of variants and of the penetrance of clinical CF, notably in inconclusive diagnosis. The penetrance of CF is defined as the risk of a particular genotype to lead to a CF phenotype.MethodsWe aimed to get insight into the penetrance of CF for fifteen CFTR variants: 5 frequent CF-causing and 10 classified as of varying clinical consequence (VCC) or associated with a CFTR-related disorder (CFTR-RD) in CFTR2 or CFTR-France databases. The penetrance was approached by: (1) comparison of variant allelic frequencies in CF patients (CFTR2) and in the general population; (2) estimation of the likelihood of a positive NBS test for the 14 compound heterozygous with F508del and the F508del homozygous genotypes, defined as the ratio of detected/expected number of neonates with a given genotype in the 2002–2017 period.ResultsA full penetrance was observed for severe CF-causing variants. Five variants were more frequently found in the general population than in CF patients: TG11T5, TG12T5, TG13T5, L997F and R117H;T7. The likelihood of a positive NBS test was 0.03% for TG11T5, 0.3% for TG12T5, 1.9% for TG13T5, 0.6% for L997F, 11.7% for D1152H, and 17.8% for R117H;T7. Penetrance varied greatly for variants with discrepant classification between CFTR2 and CFTR-France: 5.1% for R117C, 12.3% for T338I, 43.5% for D110H and 52.6% for L206W.ConclusionThese results illustrate the contribution of genetics population data to assess the disease liability of variants for diagnosis and genetic counselling purposes.     

ECFS standards of care on CFTR-related disorders: Diagnostic criteria of CFTR dysfunction

The spectrum of disorders involving CFTR (cystic fibrosis transmembrane conductance regulator) dysfunction correlates with a continuous gradient of CFTR function defined by the combination of two allelic CFTR variants. CFTR-related disorders are clinical entities with features of cystic fibrosis (CF) and evidence for presence of CFTR dysfunction but not meeting criteria for diagnosis of CF. Individuals with CFTR-RDs demonstrate a wide range of CFTR activity and are still under-recognized or misclassified. The level of CFTR dysfunction may be measured in vivo (sweat testing, nasal potential difference measurements) and/or by ex vivo tests (intestinal current measurement), or indirectly indicated by CFTR variants, as alteration in sequence of the CFTR gene translates into CFTR dysfunction. CFTR bioassays can aid in the diagnosis of individuals with CF, but we lack parameters to differentiate CF from CFTR-RD. In the era of the CFTR modulators and their potential clinical benefit, it is of utmost importance to diagnose CFTR-RD as unambiguously as possible. We therefore propose the following to define compatible CFTR dysfunction in a person with a suspected diagnosis of CFTR-RD :(1) evidence of CFTR dysfunction in vivo or ex vivo in at least two different CFTR functional test types, or(2) One CFTR variant known to reduce CFTR function and evidence of CFTR dysfunction in vivo or ex vivo in at least two different CFTR functional test types, or(3) Two CFTR variants shown to reduce CFTR function, with at most one CF-causing variant.     

Severity of the S1251N allele in cystic fibrosis is affected by the presence of the F508C variant in cis

BackgroundIn cystic fibrosis (CF), genotype-phenotype correlation is complicated by the large number of CFTR variants, the influence of modifier genes, environmental effects, and the existence of complex alleles. We document the importance of complex alleles, in particular the F508C variant present in cis with the S1251N disease-causing variant, by detailed analysis of a patient with CF, with the [S1251N;F508]/G542X genotype and a very mild phenotype, contrasting it to that of four subjects with the [S1251N;F508C]/F508del genotype and classical CF presentation.MethodsGenetic differences were identified by Sanger sequencing and CFTR function was quantified using rectal organoids in rectal organoid morphology analysis (ROMA) and forskolin-induced swelling (FIS) assays. CFTR variants were further characterised in CF bronchial epithelial (CFBE) cell lines. The impact of involved amino acid changes in the CFTR 3D protein structure was evaluated.ResultsOrganoids of the patient [S1251N;F508] with mild CF phenotype confirmed the CF diagnosis but showed higher residual CFTR function compared to the four others [S1251N;F508C]. CFBE cell lines showed a decrease in [S1251N;F508C]-CFTR function but not in processing when compared to [S1251N;F508]-CFTR. Analysis of the 3D CFTR structure suggested an additive deleterious effect of the combined presence of S1251N and F508C with respect to NBD1-2 dimerisation.ConclusionsIn vitro and in silico data show that the presence of F508C in cis with S1251N decreases CFTR function without affecting processing. Complex CFTR alleles play a role in clinical phenotype and their identification is relevant in the context of personalised medicine for each patient with CF.     

Extensive CFTR sequencing through NGS in Brazilian individuals with cystic fibrosis: unravelling regional discrepancies in the country

BackgroundThe Brazilian population has a tri-hybrid composition with a high degree of ethnic admixture. We hypothesized that Brazilian individuals with CF from different Brazilian regions have a specific distribution of CFTR variants.MethodsIndividuals with CF with data available in the Patient Registry and without an established genotype were submitted to CFTR sequencing by Next Generation Sequencing (NGS) methodology, and results were anonymously incorporated to the Registry Database. Genotyping results were expressed as ‘positive’, ‘inconclusive’ or ‘negative’. Logistic regression models were performed to investigate the association between demographic/clinical variables and genotyping results. Mediation analysis was conducted to estimate direct and indirect effects of Brazilian region on a binary positive genotyping response.ResultsIn October 2017, data from 4,654 individuals with CF were available, and 3,104(66.7%) of them had a genotyping result. A total of 236 variants (114 new variants) were identified, with F508del identified in 46% of the alleles tested. Genotyping revealed 2,002(64.5%) individuals positive, 757(24.4%) inconclusive and 345(11.1%) negative. Distribution of genotype categories was markedly different across Brazilian Regions, with greater proportions of negative individuals in the North (45%) and Northeast (26%) regions. Newborn screening (CF-NBS) and age at diagnosis were identified as mediators of the effect of Brazilian region on a positive genotyping result.ConclusionsThis large initiative of CFTR genotyping showed significant regional discrepancies in Brazil, probably related to socio-economic conditions, lack of adequate CF-NBS and poor access to reliable sweat testing. These results may be useful to indicate Regions where CF care demands more attention.     

Mutations in the cystic fibrosis transmembrane conductance regulator (CFTR) in Chinese patients with congenital bilateral absence of vas deferens

BackgroundGenetic testing of the cystic fibrosis transmembrane conductance (CFTR) gene is currently performed in patients with congenital bilateral absence of vas deferens (CBAVD). This study was conducted to investigate the role of mutations in the CFTR gene in CBAVD-dependent male infertility.Methods73 Chinese patients diagnosed with CBAVD were studied. The entire coding regions and splice sites of 27 exons of the CFTR gene were sequenced in 146 chromosomes from the 73 CBAVD patients. Screening was carried out using PCR, gel electrophoresis and DNA sequencing to identify novel variants of the entire coding regions and boundaries of the 27 exons.ResultsFive novel nonsynonymous mutations, three novel splice site mutations and one deletion were identified by sequencing. Apart from the novel variants, we also found 19 previously reported mutations and polymorphism sites. Thirty-four patients (46.57%) had the 5T variant (6 homozygous and 28 heterozygous) and in two of them it was not associated with any detectable mutation of the CFTR gene. All potential pathogenic mutations are not contained in the 1000 Genome Project database. In total, the present study identified 30 potential pathogenic variations in the CFTR gene, 9 of which had not previously been described.ConclusionsMost patients with CBAVD have mutations in the CFTR gene. A mild genotype with one or two mild or variable mutations was observed in all the patients. These findings improve our understanding of the distribution of CFTR alleles in CBAVD patients and will facilitate the development of more sensitive CFTR mutation screening.     

Distribution of CFTR mutations in the Czech population: Positive impact of integrated clinical and laboratory expertise,detection of novel/de novo alleles and relevance for related/derived populations

BackgroundThis two decade long study presents a comprehensive overview of the CFTR mutation distribution in a representative cohort of 600 Czech CF patients derived from all regions of the Czech Republic.MethodsWe examined the most common CF-causing mutations using the Elucigene CF-EU2v1? assay, followed by MLPA, mutation scanning and/or sequencing of the entire CFTR coding region and splice site junctions.ResultsWe identified 99.5% of all mutations (1194/1200 CFTR alleles) in the Czech CF population. Altogether 91 different CFTR mutations, of which 20 were novel, were detected. One case of de novo mutation and a novel polymorphism was revealed.ConclusionThe commercial assay achieved 90.7%, the MLPA added 1.0% and sequencing increased the detection rate by 7.8%. These comprehensive data provide a basis for the improvement of CF DNA diagnostics and/or newborn screening in our country. In addition, they are relevant to related Central European populations with lower mutation detection rates, as well as to the sizeable North American “Bohemian diaspora”.     

Genetics of CFTR and male infertility

Cystic fibrosis (CF) is a rare autosomal-recessive disorder manifested as multisystem organ dysfunction. The cystic fibrosis transmembrane conductance regulator (CFTR) protein functions as an ion transporter on the epithelium of exocrine glands, regulating secretion viscosity. The CFTR gene, encoded on chromosome 7, is required for the production and trafficking of the intact and functional CFTR protein. Literally thousands of human CFTR allelic mutations have been identified, each with varying impact on protein quality and quantity. As a result, individuals harboring CFTR mutations present with a spectrum of symptoms ranging from CF to normal phenotypes. Those with loss of function but without full CF may present with CFTR-related disorders (CFTR-RDs) including male infertility, sinusitis, pancreatitis, atypical asthma and bronchitis. Studies have demonstrated associations between higher rates of CFTR mutations and oligospermia, epididymal obstruction, congenital bilateral absence of the vas deferens (CBAVD), and idiopathic ejaculatory duct obstruction (EDO). Genetic variants are detected in over three-quarters of men with CBAVD, the reproductive abnormality most classically associated with CFTR aberrations. Likewise, nearly all men with clinical CF will have CBAVD. Current guidelines from multiple groups recommend CFTR screening in all men with clinical CF or CBAVD though a consensus on the minimum number of variants for which to test is lacking. CFTR testing is not recommended as routine screening for men with other categories of infertility. While available CFTR panels include 30 to 96 of the most common variants, complete gene sequencing should be considered if there is a high index of suspicion in a high-risk couple (e.g., partner is CFTR mutation carrier). CF treatments to date have largely targeted end-organ complications. Novel CFTR-modulator treatments aim to directly target CFTR protein dysfunction, effectively circumventing downstream complications, and possibly preventing symptoms like vasal atresia at a young age. Future gene therapies may also hold promise in preventing or reversing genetic changes that lead to CF and CFTR-RD.     

Expression of the inflammatory regulator A20 correlates with lung function in patients with cystic fibrosis

BackgroundA20 and TAX1BP1 interact to negatively regulate NF-κB-driven inflammation. A20 expression is altered in F508del/F508del patients. Here we explore the effect of CFTR and CFTR genotype on A20 and TAX1BP1 expression. The relationship with lung function is also assessed.MethodsPrimary nasal epithelial cells (NECs) from CF patients (F508del/F508del, n = 7, R117H/F508del, n = 6) and controls (age-matched, n = 8), and 16HBE14o- cells were investigated. A20 and TAX1BP1 gene expression was determined by qPCR.ResultsSilencing of CFTR reduced basal A20 expression. Following LPS stimulation A20 and TAX1BP1 expression was induced in control NECs and reduced in CF NECs, broadly reflecting the CF genotype: F508del/F508del had lower expression than R117H/F508del. A20, but not TAX1BP1 expression, was proportional to FEV₁ in all CF patients (r = 0.968, p < 0.001).ConclusionsA20 expression is reduced in CF and is proportional to FEV₁. Pending confirmation in a larger study, A20 may prove a novel predictor of CF inflammation/disease severity.     

CFTR modulator theratyping: Current status,gaps and future directions

Background

New drugs that improve the function of the cystic fibrosis transmembrane conductance regulator (CFTR) protein with discreet disease-causing variants have been successfully developed for cystic fibrosis (CF) patients. Preclinical model systems have played a critical role in this process, and have the potential to inform researchers and CF healthcare providers regarding the nature of defects in rare CFTR variants, and to potentially support use of modulator therapies in new populations.

Frequency of the hyperactive W493R ENaC variant in carriers of a CFTR mutation

BackgroundThe basic defect of the autosomal recessive disorder cystic fibrosis (CF) manifests in chloride hyposecretion and sodium hyperabsorption. CF-like disease has been reported in a heterozygous carrier of F508del CFTR and the hyperactive variant p.W493R-SCNN1A of the epithelial sodium channel (ENaC).MethodsThe hypothesis that heterozygosity for p.W493R-SCNN1A and one loss-of-function CFTR mutation causes or predisposes to CF or CF-like disease was tested in 441 parents of a child with CF.Resultsp.W493R-SCNN1A was detected in three female carriers of F508del CFTR who did not show any symptoms of respiratory or intestinal disease that could be interpreted as the manifestation of CF or CFTR-related disorder. Frequency of p.W493R was lower in CF parents than in Caucasian control subjects.ConclusionsA hyperactive ENaC does not necessarily cause CF-like disease in a CF gene carrier, but its low frequency in CF parents suggests that it is a risk factor.     

Is there evidence for correct diagnosis in cystic fibrosis registries?

BackgroundCystic fibrosis (CF) spans a wide spectrum. Therefore, benchmarking between registries implies comparing similar cohorts.Objective and methodsExplore patient characteristics in Belgian (B), French (F), German (G) and Dutch (NL) registries (total N = 13,122) and determine whether they fulfill predefined diagnostic criteria.ResultsUsing as case definition sweat chloride > 60 mmol/L or 2 CFTR mutations identified, CF diagnosis was not documented in 2.8, 5.7, 6.5 and 21.6% of subjects in the F, B, NL, and G registries. Restricting CFTR mutation interpretation to 124 CF causing mutations in CFTR2, these numbers rose to 10.5, 10.4, 14.5 and 24.3% respectively. Excluding these subjects impacted on outcomes. The impact differed between countries; the largest changes seen were a decrease in % adults from 51.9 to 47.8% in G, a decrease in % pancreas sufficiency from 17.0 to 13.0 in F, an increase in % homozygous for F508del from 55.3 to 63.7 in NL and a decrease of % with sweat chloride ≤ 60 mmol/L from 8.4 to 1.1 in B.ConclusionCF diagnosis is not documented in 10 to 24% of patients included in CF registries. Excluding these patients for analyses leads to significant changes in outcomes.     

Clinical outcomes of a large cohort of individuals with the F508del/5T;TG12 CFTR genotype

BackgroundIn recent years, patients with cystic fibrosis (CF) conductance regulator (CFTR) variant poly(T) sequences have been increasingly reported with a wide spectrum of clinical severity. We describe the long-term clinical outcomes and progression to a CF diagnosis over time in a large Italian cohort of patients carrying the CFTR F508del/5T;TG12 genotype.MethodsA retrospective analysis of subjects from 10 CF centres in Italy with the F508del/5T;TG12 genotype was performed. Demographic, clinical, microbiological, and biochemical data, as well as information about the follow-ups and complications of the enroled patients, were collected.ResultsA total of 129 subjects (54 females; median age: 15.0 years, range: 0–58 years; 59 older than 18 years) were included. In terms of initial diagnoses, 30 were CF (23.3%), 41 were CFTR-related disorder (CFTR-RD) (31.7%), and 58 were CF transmembrane conductance regulator-related metabolic syndrome/cystic fibrosis screen positive, inconclusive diagnosis (CRMS/CFSPID) (45.0%). After a median follow-up of 6.7 years (range 0.2–25 years), 15 patients progressed to CF, bringing the total number of CF diagnoses to 45/129 (34.9%). Most of these patients had mild lung diseases with pancreatic sufficiency and a low prevalence of CF-related complications.ConclusionsAt the end of the study, 34.9% of subjects with the CFTR F508del/5T;TG12 genotype were diagnosed with CF. We suggest including patients with the F508del/5T;TG12 genotype in long-term follow-ups.     

Anti-inflammatory effects of lenabasum,a cannabinoid receptor type 2 agonist,on macrophages from cystic fibrosis

BackgroundLenabasum is an oral synthetic cannabinoid receptor type 2 agonist previously shown to reduce the production of key airway pro-inflammatory cytokines known to play a role in cystic fibrosis (CF). In a double-blinded, randomized, placebo-control phase 2 study, lenabasum lowered the rate of pulmonary exacerbation among patients with CF. The present study was undertaken to investigate anti-inflammatory mechanisms of lenabasum exhibits in CF macrophages.MethodsWe used monocyte-derived macrophages (MDMs) from healthy donors (n = 15), MDMs with CFTR inhibited with C-172 (n = 5) and MDMs from patients with CF (n = 4). Monocytes were differentiated to macrophages and polarized into classically activated (M1) macrophages by LPS or alternatively activated (M2) macrophages by IL-13 in presence or absence of lenabasum.ResultsLenabasum had no effect on differentiation, polarization and function of macrophages from healthy individuals. However, in CF macrophages lenabasum downregulated macrophage polarization into the pro-inflammatory M1 phenotype and secretion of the pro-inflammatory cytokines IL-8 and TNF-α in a dose-dependent manner. An improvement in phagocytic activity was also observed following lenabasum treatment. Although lenabasum did not restore the impaired polarization of anti-inflammatory M2 macrophage, it reduced the levels of IL-13 and enhanced the endocytic function of CF MDMs. The effects of lenabasum on MDMs with CFTR inhibited by C-172 were not as obvious.ConclusionIn CF macrophages lenabasum modulates macrophage polarization and function in vitro in a way that would reduce inflammation in vivo. Further studies are warranted to determine the link between activating the CBR2 receptor and CFTR.     

Targeted resequencing of the 13q13 spondyloarthritis-linked locus identifies a rare variant in FREM2 possibly associated with familial spondyloarthritis

ObjectivesThe strong heritability of spondyloarthritis remains poorly explained, despite several large-scale association studies. A recent linkage analysis identified a new region linked to SpA on 13q13. Here we searched for variants potentially explaining this linkage signal by deep-sequencing of the region.MethodsRe-sequencing of the 1.4 Mb target interval was performed in 92 subjects from the 43 best-linked multicases families (71 spondyloarthritis and 21 unaffected relatives), using hybridization capture-based protocol (Illumina Nextera®). Variants of interest were then genotyped by TaqMan and high resolution melting to check their co-segregation with disease in the same families and to test their association with spondyloarthritis in an independent cohort of 1,091 unrelated cases and 399 controls. Expression of FREM2 was assessed by immunostaining.ResultsOf the 7,563 variants identified, 24 were non-synonymous coding single-nucleotide variants. Two of them were located in the FREM2 gene on a haplotype co-segregating with the disease, including one common variant (R1840 W, minor allele frequency = 0.11) and one rare variant (R727H, minor allele frequency = 0.0001). In the case-control analysis, there was no significant association between R1840 W and spondyloarthritis (P-value = 0.21), whereas R727H was not detected in any of the genotyped individuals. Immunostaining experiments revealed that FREM2 is expressed in synovial membrane, cartilage and colon.ConclusionsTargeted re-sequencing of a spondyloarthritis-linked region allowed us to identify a rare non-synonymous coding variant in FREM2, co-segregating with spondyloarthritis in a large family. This gene is expressed in several tissues relevant to spondyloarthritis pathogenesis, supporting its putative implication in spondyloarthritis.     

Lymphocyte responses to Mycobacterium tuberculosis and Mycobacterium bovis are similar between BCG-vaccinated patients with cystic fibrosis and healthy controls

BackgroundThe low rate of nontuberculous mycobacteria (NTM) among Brazilian patients with cystic fibrosis (CF) may be due to cross-reactive Bacille Calmette-Guérin (BCG) vaccination. In the present pilot study, we aimed to compare the lymphocyte responses against Mycobacterium tuberculosis(Mtb) and Mycobacterium bovis (BCG) in BCG-vaccinated CF patients and healthy controls.MethodsThe lymphocyte responses of CF patients (n = 10) and healthy controls (n = 10) were assessed in terms of lymphocyte proliferation index (LPI), using flow cytometry. Median rates of each cell subtype - CD4, CD8, γδ T cells and CD19 (B) cells - were also determined.ResultsMedian LPIs (CF vs. controls) were 22.9% vs. 13.0% (p = 0.481) and 23.1% vs. 17.6% (p = 0.481), upon stimulation with Mtb and BCG, respectively. Both groups had a predominant CD4 T cell response to Mtb (median rate = 82.5% vs. 79.7%; p = 0.796) and BCG (LPI = 84.3% vs. 83.0%; p = 0.853), which were significantly higher than the CD8, CD19 and γδ responses within both groups. CF patients tended to have a higher CD8 T cell response upon stimulation with the phytohemagglutinin mitogen than healthy controls (median rate = 42.8% vs. 31.7%, p = 0.075).ConclusionThe responses of BCG-vaccinated CF patients to Mtb and BCG are at least similar to those of healthy individuals. These are probably memory responses elicited by the BCG vaccination, which can cross-react with NTM and may explain the low frequency of NTM lung infection in our CF center.     

Low body mass index as a barrier to lung transplant in cystic fibrosis

RationaleLow body mass index (BMI) may influence lung transplant decisions for patients with advanced cystic fibrosis (CF) lung disease.ObjectiveDetermine whether patients with advanced CF lung disease and BMI ≤17 kg/m² are less likely to be listed for lung transplant or have a higher risk of death without listing compared to those with higher BMI.MethodsUsing merged United Network for Organ Sharing and CF Foundation Patient Registries, we identified adults with onset of advanced lung disease (FEV₁ ≤ 40% predicted) between May-2005 and December-2016. We analyzed survival using competing risks regression with cause-specific risks of listing for lung transplant and death without listing. BMI ≤ 17 kg/m² was our predictor.Measurements and main resultsAmong 5,121 CF patients with advanced lung disease, 23% were listed for lung transplant (n = 1,201), 23% died without listing (n = 1,190), and 44% were alive without listing (n = 2,730) as of December-2016. Patients with BMI ≤ 17 kg/m² were less likely to be listed for transplant (HR 0.69; 95% CI 0.57, 0.83) and more likely to die without listing (HR 1.63; 95% CI 1.41, 1.88). We identified important regional variations in the likelihood of referral and listing, based on BMI.ConclusionsPatients with advanced CF lung disease and BMI ≤ 17 kg/m² are less likely to be listed for lung transplant and have a higher risk of dying without listing, compared to those with higher BMI. Regional differences suggest access to transplant for malnourished CF patients may be limited by location.     

Outcomes of pregnancy in women with cystic fibrosis (CF) taking CFTR modulators – an international survey

BackgroundAs their long-term prognosis improves, women with CF are increasingly choosing to have children, but the safety of CFTR modulators in pregnancy and breastfeeding is currently unknown.MethodsA survey was sent to lead clinicians of adult CF centres in Europe, the United Kingdom (UK), United States of America (USA), Australia and Israel requesting anonymised data on pregnancy outcomes in women using CFTR modulators before and during pregnancy and lactation.ResultsWe identified 64 pregnancies in 61 women taking IVA (n = 31), LUM/IVA (n = 26) or TEZ/IVA (n = 7), resulting in 60 live births. In 44 pregnancies, CFTR modulators were either continued throughout pregnancy or temporarily stopped and then restarted. Two maternal complications were deemed related to CFTR modulator therapy; cessation of modulator therapy resulted in clinical decline in 9 women prompting resumption of therapy during pregnancy. No modulator-related complications were reported in infants exposed in utero and/or during breastfeeding.ConclusionsCFTR modulators were reported to be generally well tolerated in pregnancy and breastfeeding, with only 2 maternal complications that were deemed related to CFTR modulator therapy. Women stopping CFTR modulators in pregnancy may experience a decline in clinical status and in the cases identified in this survey, restarting therapy led to a clinical improvement. Current experience remains limited and longer-term prospective follow-up is required to exclude delayed adverse effects.