Reclassifying inconclusive diagnosis for Cystic Fibrosis with new generation sweat test

CFTR function is impaired in a subset of patients with pancreatitis carrying rare CFTR variants

BACKGROUND

Many affected by pancreatitis harbor rare variants of the cystic fibrosis (CF) gene, CFTR, which encodes an epithelial chloride/bicarbonate channel. We investigated CFTR function and the effect of CFTR modulator drugs in pancreatitis patients carrying CFTR variants.

METHODS

Next-generation sequencing was performed to identify CFTR variants. Sweat tests and nasal potential difference (NPD) assays were performed to assess CFTR function in vivo. Intestinal current measurement (ICM) was performed on rectal biopsies. Patient-derived intestinal epithelial monolayers were used to evaluate chloride and bicarbonate transport and the effects of a CFTR modulator combination: elexacaftor, tezacaftor and ivacaftor (ETI).

RESULTS

Of 32 pancreatitis patients carrying CFTR variants, three had CF-causing mutations on both alleles and yielded CF-typical sweat test, NPD and ICM results. Fourteen subjects showed a more modest elevation in sweat chloride levels, including three that were provisionally diagnosed with CF. ICM indicated impaired CFTR function in nine out of 17 non-CF subjects tested. This group of nine included five carrying a wild type CFTR allele. In epithelial monolayers, a reduction in CFTR-dependent chloride transport was found in six out of 14 subjects tested, whereas bicarbonate secretion was reduced in only one individual. In epithelial monolayers of four of these six subjects, ETI improved CFTR function.

CONCLUSIONS

CFTR function is impaired in a subset of pancreatitis patients carrying CFTR variants. Mutations outside the CFTR locus may contribute to the anion transport defect. Bioassays on patient-derived intestinal tissue and organoids can be used to detect such defects and to assess the effect of CFTR modulators.

Biochemical and genetic tools to predict the progression to Cystic Fibrosis in CRMS/CFSPID subjects: A systematic review

OBJECTIVES

Aim of this study was to identify risk factors for a progression to cystic fibrosis (CF) in individuals detected as CF Screening Positive, Inconclusive Diagnosis (CFSPID).

METHODS

This is a systematic review through literature databases (2015-2023). Blood immunoreactive trypsinogen (b-IRT) values, CFTR genotype, sweat chloride (SC) values, isolation of Pseudomonas aeruginosa (Pa) from respiratory samples, Lung Clearance Index (LCI) values in CFSPIDs who converted to CF (CFSPID > CF) and age at CF transition were assessed.

RESULTS

Percentage of CFSPID > CF varies from 5.3 % to 44 %. Presence of one CF-causing CFTR variant in trans with a variant with variable clinical consequences (VVCC), an initial SC ≥ 40 mmol/L, an increase of SC > 2.5 mmol/L/year and recurrent isolation of pseudomonas aeruginosa (Pa) from airway samples could allow identification of subjects at risk of progression to CF.

CONCLUSIONS

CFSPIDs with CF causing variant/VVCC genotype and first SC in the higher borderline range may require more frequent and prolonged clinical follow-up.

Video-assisted thoracoscopic surgery for non-cystic fibrosis bronchiectasis in children

BACKGROUND

Pediatric bronchiectasis is a common respiratory disease in children. The use of video-assisted thoracoscopic surgery (VATS) for its treatment remains controversial.

OBJECTIVES

The objective of our study was to compare and analyze the clinical efficacy of thoracoscopic surgery and thoracotomy in the treatment of pediatric bronchiectasis and summarize the surgical treatment experience of VATS in children with bronchiectasis.

DESIGN

Retrospective single-center cohort study.

METHODS

A retrospective analysis was conducted on the clinical data of 46 pediatric patients who underwent surgery with bronchiectasis at the Children's Hospital of Chongqing Medical University from May 2015 to May 2023. The patients were divided into two groups: the VATS group (25 cases) and the thoracotomy group (21 cases). Comparative analysis was performed on various parameters including basic clinical data, surgical methods, operation time, intraoperative blood loss, transfusion status, postoperative pain, postoperative mechanical ventilation time, chest tube drainage time, length of hospital stay, incidence of complications, and follow-up information.

RESULTS

There were no statistically significant differences between the two groups of patients in terms of age, weight, gender, etiology, duration of symptoms, site of onset, and comorbidities (p > 0.05). The operation time in the VATS group was longer than that in the thoracotomy group (p < 0.001). However, the VATS group had better outcomes in terms of intraoperative blood loss, transfusion status, postoperative pain, postoperative mechanical ventilation time, chest tube drainage time, and length of hospital stay (p < 0.05). The incidence of postoperative complications in the VATS group was lower than that in the thoracotomy group, although the difference was not statistically significant (p = 0.152). Follow-up data showed no statistically significant difference in the surgical treatment outcomes between the two groups (p = 0.493).

CONCLUSION

The incidence of complications and mortality in surgical treatment of bronchiectasis is acceptable. Compared with thoracotomy surgery, VATS has advantages such as smaller trauma, less pain, faster recovery, and fewer complications. For suitable pediatric patients with bronchiectasis, VATS is a safe and effective surgical method.

β-adrenergic sweat test in children with inconclusive cystic fibrosis diagnosis: Do we need new reference ranges?

BACKGROUND

Investigating inconclusive cystic fibrosis (CF) diagnosis in children is difficult without advanced cystic fibrosis transmembrane conductance regulator (CFTR) function tests. This study investigated the utility of beta (β)-adrenergic sweat test to exclude CF in participants with inconclusive diagnosis (CF suspects) in South Africa.

METHODS

β-adrenergic sweat test and sweat chloride tests (SCT) were performed simultaneously in CF suspects and adult controls (healthy, CFTR heterozygotes and CF). Cholinergic and β-adrenergic induced sweat rate was measured by evaporimetry (transepithelial water loss [TEWL]: g H₂ O/m² /h) following intradermal injections. Next-generation sequencing of CFTR was performed in CF suspects. CF diagnosis was defined by genotype.

RESULTS

Thirty-seven controls (10 healthy, 14 CF, 13 CFTR heterozygotes) and 32 CF suspects (26 children; 6 adults) were enrolled. Six were excluded from formal analyses due to β-adrenergic sweat test failure. In adults, evaporimetry was superior to SCT for diagnosis of CF with β-adrenergic:cholinergic ratio TEWL ≤ 0.05 achieving 100% sensitivity and specificity. Twenty-two CF suspect children (age range: 3.4-15.6 years) completed β-adrenergic sweat testing of which none had CF confirmed by genotyping: β-adrenergic:cholinergic ratio > 0.05 successfully excluded CF in all but one child who was CFTR heterozygous. Median peak β-adrenergic TEWL and β-adrenergic:cholinergic ratio in CFTR negative and CFTR heterozygous children was significantly lower than adult controls.

CONCLUSION

β-adrenergic sweat test is more accurate than SCT for excluding CF in children with inconclusive diagnosis. Established reference ranges for β-adrenergic sweat test may not be suitable for children due to lower β-adrenergic sweat secretion compared to adults.