Mild CF in a delta F508/R347H compound heterozygote woman: does the manifestation of this genotype differ in the two sexes?

Whole Exome Sequencing Identifies a Rare CFTR Mutation in Brothers With Anomalies of the Vas Deferens: A Case Study

Congenital bilateral absence of the vas deferens (CBAVD) occurs in almost all men with cystic fibrosis. Prevailing theories on this pathophysiology relate to pathogenic mutations in the cystic fibrosis transmembrane regulator gene leading to agenesis or obliteration of vas deferens in utero. In this study, we present a case of two brothers with congenital anomalies of the vas deferens who were found to have carried a rare, heterozygous cystic fibrosis transmembrane regulator variant p.r347h without pulmonary or gastrointestinal signs or symptoms of cystic fibrosis .

Current challenges in cystic fibrosis screening

CONTENT

This article gives an overview of the symptoms and mutations associated with classic and atypical cystic fibrosis (CF). Current testing methods for mutation detection in CF are discussed.

OBJECTIVES

Review testing for CF, including American College of Medical Genetics and American College of Obstetrics and Gynecology guidelines and recommendations regarding population screening for CF. Describe symptomatic and mutational differences between patients with classic CF and atypical CF, including monosymptomatic conditions such as congenital bilateral absence of the vas deferens, idiopathic pancreatitis, and chronic sinusitis. Explain the concern about predicting the phenotypic expression of the condition from the genotype. Discuss the challenges of CF testing, including the preanalytic, analytic, and postanalytic phases. List the current methods for detecting CF transmembrane conductance regulator gene mutations, specifying the advantages and disadvantages of each. Describe the basic patient information necessary for laboratories to provide accurate risk assessments, such as ethnicity and family history, and reasons for the test being conducted (carrier or affected status).

RESULTS

The technical challenges of detecting the 25 recommended mutations are being met by commercially available reagents. Challenges remain for the preanalytic and postanalytic phases. Only with accurate patient information can laboratories provide specific risk reductions on the basis of a negative genetic test result.

CONCLUSION

As health care providers become better informed about the recommendations for CF testing and laboratories continue to increase the sensitivities of their assays, patients will benefit from increased screening efficiency and accuracy. This will allow affected individuals to receive prompt and effective treatment and carriers to enjoy an expanded number of reproductive options.

Mutations of the cystic fibrosis gene and intermediate sweat chloride levels in children

The incidence of mutations of the cystic fibrosis transmembrane conductance regulator (CFTR) gene in children with intermediate sweat chloride levels is unknown. The results of 2,349 sweat tests performed at two Belgian university hospitals were reviewed. Intermediate chloride concentrations were observed in 98 subjects (4.2%), 68 being younger than 18 years of age. Forty-three children could be traced and their parents agreed to take part in the study. Exhaustive analysis of the CFTR gene disclosed a total of 24 putative mutations (27.9%). Three subjects were found to carry only one CFTR mutation, whereas 10 harbored one mutation on both CFTR genes. These 10 children were investigated in detail. At the time of writing, the mean age (+/-SD) of this group is 8.9 years (+/-4.2 years). Nine children are pancreatic sufficient. Three have been asymptomatic for more than two years, whereas the others display, to different degrees, clinical features suggestive of CF. The sweat chloride concentration is slightly higher in this group (39.4 +/- 5.4 mM) than in subjects without CFTR mutation (35.2 +/- 4.4 mM, p < 0.05). The nasal potential difference was abnormal in five of the nine subjects tested. In this study, 23% of children displaying intermediate sweat chloride levels were found to carry a putative mutation on both CFTR genes.