Diagnosis of cystic fibrosis in the kindred of an infant with CFTR-related metabolic syndrome: importance of follow-up that includes monitoring sweat chloride concentrations over time

Cystic Fibrosis Foundation Evidence-Based Guideline for the Management of CRMS/CFSPID

A multidisciplinary committee developed evidence-based guidelines for the management of cystic fibrosis transmembrane conductance regulator-related metabolic syndrome/cystic fibrosis screen-positive, inconclusive diagnosis (CRMS/CFSPID). A total of 24 patient, intervention, comparison, and outcome questions were generated based on surveys sent to people with CRMS/CFSPID and clinicians caring for these individuals, previous recommendations, and expert committee input. Four a priori working groups (genetic testing, monitoring, treatment, and psychosocial/communication issues) were used to provide structure to the committee. A systematic review of the evidence was conducted, and found numerous case series and cohort studies, but no randomized clinical trials. A total of 30 recommendations were graded using the US Preventive Services Task Force methodology. Recommendations that received ≥80% consensus among the entire committee were approved. The resulting recommendations were of moderate to low certainty for the majority of the statements because of the low quality of the evidence. Highlights of the recommendations include thorough evaluation with genetic sequencing, deletion/duplication analysis if <2 disease-causing variants were noted in newborn screening; repeat sweat testing until at least age 8 but limiting further laboratory testing, including microbiology, radiology, and pulmonary function testing; minimal use of medications, which when suggested, should lead to shared decision-making with families; and providing communication with emphasis on social determinants of health and shared decision-making to minimize barriers which may affect processing and understanding of this complex designation. Future research will be needed regarding medication use, antibiotic therapy, and the use of chest imaging for monitoring the development of lung disease.

Diagnostic challenges in CFTR-related metabolic syndrome: Where the guidelines fall short

Newborn screening (NBS) for cystic fibrosis (CF) has enabled earlier diagnosis and has improved nutritional and growth-related outcomes in children with CF. For those with a positive NBS for CF that do not meet the diagnostic criteria for CF, the clinical entity called CFTR-Related Metabolic Syndrome (CRMS) or CF Screen- Positive, Inconclusive Diagnosis (CFSPID) is used. Although most children with CRMS remain relatively asymptomatic, studies have shown that between 11% and 48% of these patients may eventually progress to a diagnosis of CF over time. Although the CF Foundation guidelines for CRMS management and European CF Society guidelines for CFSPID have some similarities, there are also some differences. Here, we review challenging case scenarios that highlight remaining gaps in CRMS guidelines, thus supporting the need to update and unify existing guidelines.

Stakeholder Views of the Proposed Introduction of Next Generation Sequencing into the Cystic Fibrosis Screening Protocol in England

The project aimed to gather, analyse, and compare the views of stakeholders about the proposed UK cystic fibrosis (CF) screening protocol incorporating next generation sequencing (NGS). The study design was based on principles of Q-methodology with a willingness-to-pay exercise. Participants were recruited from 12 CF centres in the UK. The study contained twenty-eight adults who have experience with CF (parents of children with CF (n = 21), including parents of children with CF transmembrane conductance regulator (CFTR)-related metabolic syndrome (CRMS)/CF screen positive-inconclusive diagnosis (CFSPID), an uncertain outcome (n = 3), and adults with CF (n = 4)), and nine health professionals involved in caring for children with CF. Parents and health professionals expressed a preference for a sensitive approach to NGS. This was influenced by the importance participants placed on not missing any children with CF via screening and the balance of harm between missing a case of CF compared to picking up more children with an uncertain outcome (CRMS/CFSPID). Given the preference for a sensitive approach, the need for adequate explanations about potential outcomes including uncertainty (CFSPID) at the time of screening was emphasized. More research is needed to inform definitive guidelines for managing children with an uncertain outcome following CF screening.

Genetic diagnosis and treatment of hereditary renal tubular disease with hypokalemia and alkalosis

Renal tubules play an important role in maintaining water, electrolyte, and acid-base balance. Renal tubule dysfunction can cause electrolyte disorders and acid-base imbalance. Clinically, hypokalemic renal tubular disease is the most common tubule disorder. With the development of molecular genetics and gene sequencing technology, hereditary renal tubular diseases have attracted attention, and an increasing number of pathogenic genes related to renal tubular diseases have been discovered and reported. Inherited renal tubular diseases mainly occur due to mutations in genes encoding various specific transporters or ion channels expressed on the tubular epithelial membrane, leading to dysfunctional renal tubular reabsorption, secretion, and excretion. An in-depth understanding of the molecular genetic basis of hereditary renal tubular disease will help to understand the physiological function of renal tubules, the mechanism by which the kidney maintains water, electrolyte, and acid-base balance, and the relationship between the kidney and other systems in the body. Meanwhile, understanding these diseases also improves our understanding of the pathogenesis of hypokalemia, alkalosis and other related diseases and ultimately promotes accurate diagnostics and effective disease treatment. The present review summarizes the most common hereditary renal tubular diseases (Bartter syndrome, Gitelman syndrome, EAST syndrome and Liddle syndrome) characterized by hypokalemia and alkalosis. Further detailed explanations are provided for pathogenic genes and functional proteins, clinical manifestations, intrinsic relationship between genotype and clinical phenotype, diagnostic clues, differential diagnosis, and treatment strategies for these diseases.

Monogenic diseases in respiratory medicine: Clinical perspectives

With the increasing awareness of genetics in respiratory medicine and improvements in molecular diagnostic techniques, many complicated and rare diseases in respiratory medicine can be diagnosed. Most respiratory diseases have no specific phenotype. However, the clinical spectrum of monogenic diseases in respiratory medicine varies, from pulmonary disease to other inherited disorders that involve the lung. The genes that mediate some of these diseases have been identified. Certain monogenic diseases remain poorly characterized clinically. Because of the specificity of the phenotype of respiratory disease, a future challenge will be to correlate the phenotype and genotype and understand its phenotypic variability. With the development of precision medicine, research on monogenic disorders has been intensive and vigorous. In this article, we provide a brief clinical introduction to monogenic diseases in pediatrics.

2014 year in review: Cystic fibrosis

In this article, we highlight cystic fibrosis (CF) research published in Pediatric Pulmonology during 2014, as well as related articles published in other journals.

Clinical evaluation of the Nanoduct sweat test system in the diagnosis of cystic fibrosis after newborn screening

After a positive newborn screening test for cystic fibrosis (CF), a sweat test is performed to confirm the diagnosis. The success rate of the generally acknowledged methods (Macroduct/Gibson and Cooke) in newborns varies between 73 and 99%. The Nanoduct sweat test system is easier to perform and less sweat is needed. The main aim of this study was to measure the success rate of the Nanoduct compared to current approved sweat test methods in a newborn population. After informed consent of the parents, newborns with a positive screening test for CF were included. The Macroduct or Gibson and Cooke and Nanoduct were performed in all infants, during the same appointment. The chloride concentration was determined by standard coulorimetry; conductivity was measured directly and converted to a NaCl molarity. One hundred eight newborns were included: 17 with CF, 7 with cystic fibrosis transmembrane regulator (CFTR)-related metabolic syndrome (CRMS), and 84 healthy children. The success rate of the Nanoduct was 93% and for the Macroduct/Gibson and Cooke 79% (McNemar, p = 0.002). The Nanoduct detected the same CF patients as the Macroduct/Gibson and Cooke; one CF patient had an equivocal result for both tests, and no patients were missed. The area under the receiver operating characteristic curve for detection of CF with the Nanoduct was 0.999, with ideal cutoff levels of 91 and 66 mmol/l, comparable to former studies.

CONCLUSION

The success rate of the Nanoduct to collect sufficient sweat in infants was higher compared to the Macroduct and Gibson and Cooke.