Analysis of CNVs of CFTR gene in Chinese Han population with CBAVD

One-step NGS molecular analysis of the CFTR gene on newborn dried blood spots gives a higher diagnostic sensitivity in affected and carrier subjects: A pilot study

BACKGROUND

Cystic fibrosis is the most common hereditary recessive disease with an incidence of about 1:2500/3000. It has long been known that the disease is caused by deleterious mutations in the CFTR gene. Conventionally, the disease is diagnosed in several phases. The analysis of all the possible disease-causing molecular alterations is time consuming and may not lead to a definitive diagnosis in several cases. Consequently, we propose, in this paper, a rapid sequencing method that, in a single procedural asset, reveals the presence of small mutations and also the copy number variants (CNVs) from the DNA extracted from the Guthrie Spot.

MATERIALS AND METHODS

We first sequenced 30 blood spots, then we validated the method on 100 spots that underwent both traditional analyses and this complete NGS sequencing, and lastly, we tested the strategy on patients who normally do not reach the molecular sequencing step because of low level of Immune-Reactive Trypsinogen.

RESULTS

Using this procedure, we identified 97 variants in the CFTR gene of our samples and 6 CNVs. Notably, the significant data were obtained in the group of patients with borderline or negative IRT who routinely would not undergo molecular testing. We also identified 6 carriers of "disease-causing" variants.

CONCLUSION

This method is very robust. Indeed, there was a 100% concordance with Sanger sequencing validation, and 6 mutation carriers were identified who normally escaped molecular testing with actual conventional procedure. There were also 3 duplications of almost the entire gene in heterozygosity, which were not seen with traditional methods. Being quick and easy to perform, we suggest that complete sequencing of the CFTR gene, as in this study be considered for all newborns.

Pathogenic Variants and Genotypes of the CFTR Gene in Russian Men with Cystic Fibrosis and CBAVD Syndrome

Pathogenic CFTR variants cause cystic fibrosis (CF), and CF-related disorders (CF-RD), including bilateral aplasia of the vas deferens (CBAVD). The spectrum of clinical manifestations depends on the CFTR genotype. The frequency and spectrum of the CFTR variants vary between populations and clinical groups. CFTR variants and genotypes were analyzed in Russian men with CF (n = 546) and CBAVD syndrome (n = 125). Pathogenic variants were detected in 93.95% and 39.2% of the CF and CBAVD alleles, respectively. The most frequent c.1521_1523del (F508del; p.Phe508del) variant was found in 541 (49.5%) CF alleles. A total of 162 CFTR genotypes were revealed in CF patients, including 152 homozygous and 394 compound-heterozygous. The most common CF-genotype was F508del/F508del (24.9%). Other frequent CF-genotypes were F508del/3849+10kbC>T, F508del/CFTRdele2,3, and F508del/E92K. CF-causing variants and/or 5T allele were found in 88% of CBAVD patients: 5T/CFTRmut (48.0%), CFTRmut/N (17.6%), CFTRmut/CFTRmut (6.4%), 5T/5T (10.4%), 5T/N (5.6%) and N/N (12.0%), with the most common CBAVD-genotype being F508del/5T (29.6%). The allele frequencies of F508del, CFTRdele2,3 394delTT, and 3849+10kbC>T were significantly higher in CF patients. L138ins/L138ins, 2184insA/E92K, and L138ins/N genotypes were found in CBAVD, but not in CF patients. The results indicate certain differences in the frequency of some CFTR variants and genotypes in Russian CF and CBAVD patients.

Cystic fibrosis transmembrane conductance regulator (CFTR): beyond cystic fibrosis

Background

The cystic fibrosis transmembrane conductance regulator (CFTR) gene has been traditionally linked to cystic fibrosis (CF) inheritance in an autosomal recessive manner. Advances in molecular biology and genetics have expanded our understanding of the CFTR gene and its encoding products expressed in different tissues.

Aim

The study’s aim consists of reviewing the different pathological CF phenotypes using the existing literature. We know that alterations of the CFTR protein’s structure may result in different pathological phenotypes.

Methods

Open sources such as PubMed and Science Direct databases have been used for this review. We focused our selection on articles published within the last 15 years. Critical terms related to the CFTR protein have been used: “CFTR AND cancer,” “CFTR AND celiac disease,” “CFTR AND pancreatitis,” “children,” “adults,” “genotype,” “phenotype,” “correlation,” “mutation,”  “CFTR,” “diseases,” “disorders,” and “no cystic fibrosis.”

Results

We analyzed 1,115 abstracts in total. Moreover, only 189 were suitable for the topic. We focused on the role of CFTR in cancer, gastrointestinal disorders, respiratory diseases, reproductive system, and systemic hypertension.

Conclusions

Mutations in CFTR gene are often associated with CF. In this review, we highlighted the broad spectrum of alterations reported for this gene, which may be involved in the pathogenesis of other diseases. The importance of these new insights in the role of CFTR relies on the possibility of considering this protein/gene as a novel therapeutic target for CF- and CFTR-related diseases.

Multicenter Surveillance of Cystic Fibrosis in Korean Children

Purpose

Methods

Results

Conclusions

Mutations in CFTR genes are associated with oligoasthenospermia in infertile men undergoing IVF

Cystic fibrosis transmembrane conductance regulator (CFTR) gene mutation has been clearly defined in congenital absence of the vas deferens (CAVD), which is an important cause of obstructive azoospermia. However, the association between oligoasthenospermia and CFTR gene mutation remains controversial. To confirm this issue, 151 infertile Chinese men were screened for CFTR mutation by NGS approach, including 18 CAVD patients, 72 patients with severe oligoasthenospermia and 61 controls with normal sperm parameters. Frequency of mutation in exons of CFTR gene were 66.7% in CAVD patients (12/18) (p < 0.001) and 8.33% in severe oligoasthenospermic patients (6/72) (p < 0.05), both of which were significantly more frequent than that in the controls (0/61). In terms of introns mutation of CFTR gene, there was no significant difference in frequency of 5T between oligoasthenospermic men (5/144, 3.47%) and the controls (4/122, 3.28%) (p = 0.645). In addition, 6 novel mutations in exons of CFTR gene in this study (c.3736A>G, c.635T>G, c.482delA, c.1858C>T, c.2042A>T, c.1586A>C) have not been reported in the Cystic Fibrosis Mutation Database before. Thus, our study provides evidence that CFTR gene mutation may be the aetiology of severe oligoasthenospermia other than CAVD. It may be necessary to screen for CFTR mutations in men with severe oligoasthenospermia before receiving assisted reproductive technology.