A systematic review of the clinical and genetic characteristics of Chinese patients with cystic fibrosis

Genetic analysis and functional study of novel CFTR variants in Chinese children with cystic fibrosis

OBJECTIVES

To describe the clinical characteristics of Chinese cystic fibrosis (CF) patients and to investigate the variants of CFTR and their potential pathogenicity.

STUDY DESIGN

Chinese patients with potential CF diagnosis were studied. Clinical data were reviewed retrospectively from medical records. Whole exome sequencing and genetic evaluation were conducted to explore potential gene variants. The disruption of the variants to protein structure and function was explored and validated using in vitro experiments and in silico analysis.

RESULTS

Four patients were recruited to the study, three of them were diagnosed as CF, and one was diagnosed as CFTR-related disorder. The age at symptom onset for the patients in this study ranged from newborn to 6 years, while the age at diagnosis varied from 3 to 11 years. All four patients exhibited bilateral diffuse bronchiectasis with Pseudomonas aeruginosa infections, and three of them had malnutrition. Finger clubbing was observed in three patients, two of whom displayed mixed ventilatory dysfunction. The CFTR variants spectrum of Chinese children with CF differs from that of Caucasian. A total of six variants were identified, two of which were first reported (c.1219G > T [p.Glu407*] and c.1367delT [p.Ala457Leufs*12]). The nonsense variants c.1219G > T, c.1657C > T and c.2551C > T and the frameshift variant c.1367delT were predicted to introduce premature stop codon and produce shorten CFTR protein, which was also first validated by in vitro truncation assay in this study. The missense variant c.1810A > C was predicted to disrupt the function of the nucleotide-binding domain 1 (NBD1) in the CFTR protein. The splicing variant c.1766 + 5G > T caused skipping of exon 13 and damaged the integrity of CFTR protein.

CONCLUSIONS

Our study expands the spectrum of phenotypes and genotypes for CF of Chinese origin, which differs significantly from that of Caucasian. Genetic analysis and counseling are crucial and deserve extensive popularization for the diagnosis ofCF in patients of Chinese origin.

[Cystic fibrosis primarily presenting with pseudo-Bartter syndrome: a report of three cases and literature review]

OBJECTIVES

To summarize the clinical characteristics and genetic variations in children with cystic fibrosis (CF) primarily presenting with pseudo-Bartter syndrome (CF-PBS), with the aim to enhance understanding of this disorder.

METHODS

A retrospective analysis was performed on the clinical data of three children who were diagnosed with CF-PBS in Hunan Children's Hospital from January 2018 to August 2023, and a literature review was performed.

RESULTS

All three children had the onset of the disease in infancy. Tests after admission showed hyponatremia, hypokalemia, hypochloremia, and metabolic alkalosis, and genetic testing showed the presence of compound heterozygous mutation in the CFTR gene. All three children were diagnosed with CF. Literature review obtained 33 Chinese children with CF-PBS, with an age of onset of 1-36 months and an age of diagnosis of 3-144 months. Among these children, there were 29 children with recurrent respiratory infection or persistent pneumonia (88%), 26 with malnutrition (79%), 23 with developmental retardation (70%), and 18 with pancreatitis or extrapancreatic insufficiency (55%). Genetic testing showed that c.2909G>A was the most common mutation site of the CFTR gene, with a frequency of allelic variation of 23% (15/66).

CONCLUSIONS

CF may have no typical respiratory symptoms in the early stage. The possibility of CF-PBS should be considered for infants with recurrent hyponatremia, hypokalemia, hypochloremia, and metabolic alkalosis, especially those with malnutrition and developmental retardation. CFTR genetic testing should be performed as soon as possible to help with the diagnosis of CF.

Clinical and genetic features of cystic fibrosis in Japan

Cystic fibrosis (CF) is an autosomal recessive disease caused by pathogenic variants in CF transmembrane conductance regulator (CFTR). While CF is the most common hereditary disease in Caucasians, it is rare in East Asia. In the present study, we have examined clinical features and the spectrum of CFTR variants of CF patients in Japan. Clinical data of 132 CF patients were obtained from the national epidemiological survey since 1994 and CF registry. From 2007 to 2022, 46 patients with definite CF were analyzed for CFTR variants. All exons, their boundaries, and part of promoter region of CFTR were sequenced and the presence of large deletion and duplications were examined by multiplex ligation-dependent probe amplification. CF patients in Japan were found to have chronic sinopulmonary disease (85.6%), exocrine pancreatic insufficiency (66.7%), meconium ileus (35.6%), electrolyte imbalance (21.2%), CF-associated liver disease (14.4%), and CF-related diabetes (6.1%). The median survival age was 25.0 years. The mean BMI percentile was 30.3%ile in definite CF patients aged < 18 years whose CFTR genotypes were known. In 70 CF alleles of East Asia/Japan origin, CFTR-dele16-17a-17b was detected in 24 alleles, the other variants were novel or very rare, and no pathogenic variants were detected in 8 alleles. In 22 CF alleles of Europe origin, F508del was detected in 11 alleles. In summary, clinical phenotype of Japanese CF patients is similar to European patients, but the prognosis is worse. The spectrum of CFTR variants in Japanese CF alleles is entirely different from that in European CF alleles.

Clinical and genetic characteristics of children with cystic fibrosis in Henan China: A single-center retrospective analysis

BACKGROUND

Despite the growing awareness of cystic fibrosis (CF) in China, few cases have been reported in Henan, which is the most populous province in the country. This study aimed to describe the clinical phenotype and genotype of children with CF in Henan.

METHODS

We retrospectively recruited 18 Chinese children with CF who presented to Children's Hospital affiliated to Zhengzhou University from January 2019 to June 2023. The demographic data, imaging examinations, and laboratory tests of the patients were reviewed to clarify the clinical phenotype. Whole exome sequencing was conducted to identify the genotype.

RESULTS

Respiratory diseases were the main clinical manifestation, including recurrent/persistent pneumonia (88.9%), sinusitis (77.8%), bronchiectasis (77.8%). CF-related liver disease and pancreatic insufficiency were less common. Infant cases had high frequency of pseudo-Bartter Syndrome (80.0%). Chest computed tomography showed bronchiectasis in older children and air trapping in infant cases. The most common pathogens in the airway were Pseudomonas aeruginosa (72.2%) and Staphylococcus aureus (66.7%). Twenty-five different cystic fibrosis transmembrane conductance regulator (CFTR) gene variants were detected, including five novel observations (c.1064C>G[p. Pro355Arg], c.1209+1G>C, c.1925C>G[p. Ser642X], c.2810T>G[p. Leu937Arg], and c.3792delA[p. Gly1265GlufsX13]). The most common variant was c.2909G>A(p. Gly970Asp), with a detected rate of 21.9%.

CONCLUSION

Children with CF in Henan had varied clinical phenotypes by age, with respiratory disease being predominant. The most frequent CFTR gene variant was c.2909G>A(p. Gly970Asp). This study is the first and most comprehensive one on the clinical phenotype and genotype of children with CF in Henan, China. We also reported the first CF case of Mycobacterium abscessus infection in China.

Morbidity and treatment costs of cystic fibrosis in a middle-income country

Introduction

: Asian children with cystic fibrosis (CF) managed in Malaysia have significant morbidity with limited access to life-sustaining treatments. We determined the morbidity and treatment cost of CF in a resource-limited country.

Methods

This cross-sectional study included all children diagnosed with CF in our centre. Data on clinical presentation, genetic mutation, serial spirometry results and complications were collected. Out-of-pocket (OOP) and healthcare costs over 1 year were retrieved for patients who were alive. Cohen's d and odds ratio (OR) were used to determine the effect size.

Results

Twenty-four patients were diagnosed with CF. Five patients died at a median (range) age of 18 (0.3-22) years. F508deletion (c. 1521_1523delCTT) was found in 20% of the alleles, while 89% of the variants were detected in nine patients. Body mass index (BMI) Z score was >-1.96 in 70.6% of patients. Two thirds (68%) were colonised with Pseudomonas aeruginosa, and this was associated with lower weight (P = 0.009) and BMI (P = 0.02) Z scores. Only 18% had FEV1 Z scores >-1.96. Early symptom onset (d = 0.74), delayed diagnosis (d = 2.07), a low FEF25-75 Z score (d = 0.82) and a high sweat conductance (d = 1.19) were associated with death. Inpatient cost was mainly from diagnostic tests, while medications contributed to half of the outpatient cost.

Healthcare utilisation cost was catastrophic, amounting to 20% of the total income.

Conclusion

Asian children with CF suffer significant complications such as low weight, low lung function and shortened lifespan. P. aeruginosa colonisation was frequent and associated with poor growth. Healthcare cost to parents was catastrophic.

Genetic spectrum of Chinese children with cystic fibrosis: comprehensive data analysis from the main referral centre in China

BACKGROUND AND OBJECTIVES

Cystic fibrosis (CF) is a heterogeneous disease with a diverse genetic spectrum among populations. Few patients with CF of Chinese origin have been reported worldwide. The objective of this study is to characterise the genotypic features of CF in Chinese children.

METHODS

We recruited and characterised the genetic manifestations of 103 Chinese children with CF in Beijing Children's Hospital from 2010 to 2022. Whole-exome sequencing were performed to define the genotypes. Meanwhile, other 99 genetically confirmed patients with Chinese origin described in 45 references were also summarised.

RESULTS

158 different variants including 23 novel observations were identified after sequencing. The majority of CFTR variants (82.3%) in Chinese have been observed only once or twice. 43.7% of the variants were only identified in patients of Chinese origin. The c.2909G>A(p.Gly970Asp), c.1766+5G>T and c.1657C>T(p.Arg553X) were the most frequent variants among Chinese patients, with allele frequency of 12.1%, 5.4% and 3.6%, respectively. The first two variants both showed significant Chinese ethnic tendency, while the latter one most likely came from Europeans for historical reasons. They also demonstrated significant differences in geographical distribution. c.1521_1523delCTT(p.F508del) was rarely observed in patients of pure Chinese origin, with an allele frequency of 1.8%. Two de novo variants (c.960dupA[p.Ser321IlefsX43] and c.2491-2A>G) and two deep-intronic variants (c.3718-2477C>T and c.3874-4522A>G) were identified, which were also quite rare among Chinese.

CONCLUSIONS

The genetic spectrum of CF in Chinese is unique and quite different from that observed in Caucasians. The geographical distributions of the most frequent variants were reported for the first time.

[Clinical and gene mutation features of cystic fibrosis: an analysis of 8 cases]

OBJECTIVES

To study the clinical features and gene mutation sites of children with cystic fibrosis (CF), in order to improve the understanding of CF to reduce misdiagnosis and missed diagnosis.

METHODS

A retrospective analysis was performed on the medical records of 8 children with CF who were diagnosed in Hebei Children's Hospital from 2018 to 2021.

RESULTS

Among the 8 children with CF, there were 5 boys and 3 girls, with an age of 3-48 months (median 8 months) at diagnosis, and the age of onset ranged from 0 to 24 months (median 2.5 months). Clinical manifestations included recurrent respiratory infection in 7 children, sinusitis in 3 children, bronchiectasis in 4 children, diarrhea in 8 children, fatty diarrhea in 3 children, suspected pancreatic insufficiency in 6 children, pancreatic cystic fibrosis in 1 child, malnutrition in 5 children, and pseudo-Bartter syndrome in 4 children. The most common respiratory pathogens were Pseudomonas aeruginosa (4 children). A total of 16 mutation sites were identified by high-throughput sequencing, multiplex ligation-dependent probe amplification, and Sanger sequencing, including 5 frameshift mutations, 4 nonsense mutations, 4 missense mutations, 2 exon deletions, and 1 splice mutation. CFTR mutations were found in all 8 children. p.G970D was the most common mutation (3 children), and F508del mutation was observed in one child. Four novel mutations were noted: deletion exon15, c.3796_3797dupGA(p.I1267Kfs*12), c.2328dupA(p.V777Sfs*2), and c.2950G>A(p.D984N).

CONCLUSIONS

p.G970D is the most common mutation type in children with CF. CF should be considered for children who have recurrent respiratory infection or test positive for Pseudomonas aeruginosa, with or without digestive manifestations or pseudo-Bartter syndrome.

Cystic fibrosis in children: A pediatric anesthesiologist's perspective

Cystic fibrosis is a multi-systemic disease of impaired sodium and chloride transport across epithelial surfaces. Cystic fibrosis is one of the most common autosomal recessive diseases among Caucasian children. However, recent epidemiologic studies suggest that the disease in Hispanic, African American, and Asian American populations may be more common than previously recognized. The phenotypic expression is characterized by the constellation of pulmonary, pancreatic, hepatobiliary, and gastrointestinal dysfunction. Progressive obstructive lung disease is the hallmark of cystic fibrosis, and end-stage respiratory failure is the primary cause of morbidity and mortality. The most significant advance in the care has been the development of cystic fibrosis modulators, a class of drugs that restore cystic fibrosis transmembrane conductance regulator folding, intracellular processing, or function. Improved diagnostic abilities, a multidisciplinary approach to medical management, and the use of cystic fibrosis modulators have led to improvement in the quality of life and life expectancy. These patients undergo range of procedures such as nasal polypectomy, placement of gastrostomy tubes, vascular access device placement, transbronchial lung biopsies, and other thoracic surgeries. The anesthetic care of children with advanced cystic fibrosis disease is complex. Preoperative optimization can help improve postoperative outcomes. Strategies for pain control should rely on non-opiate, multimodal adjuncts, and regional or neuraxial techniques. Unfortunately for some children, a progressive respiratory disease often leads to end-stage respiratory failure and lung transplant surgery remains the only viable treatment option. Widespread use of lung transplant surgery as a treatment option is severely constraint by donor organ availability. Primary graft dysfunction is the most common cause of early death and can be seen within 48 h of surgery. Median long-term survival after lung transplant remains modest. Chronic lung allograft dysfunction, opportunistic infections, and post-transplant lymphoproliferative disorder are the most common causes of morbidity and mortality among long-term survivors.

Year in Review 2020: Multisystemic impact of cystic fibrosis

Clinical care in cystic fibrosis (CF) has continued to advance over the last several years, particularly with the widespread eligibility and use of highly effective modulator therapy. Improved outcomes and longevity of persons with CF (PwCF) have increased recognition of the multisystem impact of the disease on the daily lives of PwCF. This review will cover a broad array of topics, from diagnosis to multisystem effects related to mental health, endocrine, palliative care, reproductive health, otolaryngology, and cardiac issues. Additionally, worldwide care delivery will be reviewed, demonstrating variation in outcomes based on resources and populations served. This review is part of the CF Year in Review 2020 series, focusing on the multi-system effects of CF. This review focuses on articles from Pediatric Pulmonology but also includes articles published in 2020 from other journals that are of particular interest to clinicians.

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 information toward reducing CF misdiagnosis and missed diagnosis rates.

Prognosis and treatment of 46 Chinese pediatric cystic fibrosis patients

BACKGROUND

Since public awareness of cystic fibrosis (CF) has increased, more children have been diagnosed with CF in China. This study aimed to investigate medical and other challenges faced by pediatric CF patients in China.

METHOD

Treatments and treatment outcomes were retrospectively analyzed for 46 pediatric CF patients diagnosed from August 2009 to June 2019. Pre- and post-treatment results were compared using independent samples t-test.

RESULTS

Of 46 pediatric CF study patients, four died and five were lost to follow-up. Thirty-seven patients were monitored for 0.03 to 9.21 years; patients exhibited fewer attacks of respiratory tract infections after diagnosis (4.49 ± 2.13 episodes/year before diagnosis vs 1.97 ± 1.87 times/year after 1-year treatment, p < 0.05), significantly reduced sputum production and experienced 1.62 ± 1.71 exacerbations/year. Patient mean body mass index was 16.87 ± 3.53 and pancreatic malfunction persisted in 15 patients. For 17 children, no significant differences in lung function were found at follow-up as compared to lung function at diagnosis (FEV₁: 82.45% ± 16.56% vs 75.26% ± 22.34%, FVC: 87.18% ± 13.64% vs 86.99% ± 19.95%, FEF_75%: 46.51% ± 28.78% vs 36.63% ± 24.30%, P = 0.27, 0.97, 0.20, respectively). Pseudomonas aeruginosa (17/27) and bronchiectasis (22/22) were found during follow-up evaluation. Twenty-four patients (64.8%) maintained good adherence to therapies. Overall, azithromycin and tobramycin treatments were administered for 0.5-62 months and 0.5-48 months, respectively, and triggered no obvious adverse reactions.

CONCLUSION

No obvious declines in clinical presentation or lung function were found in Chinese pediatric CF patients after receiving standard therapeutic and active treatments, although malnutrition and low compliance were persistent challenges.