[The diagnosis of cystic fibrosis in adults: lessons from a family story].

INTRODUCTION

Cystic fibrosis is usually diagnosed during the first years of life. Diagnosis may be achieved in adults with milder forms of the disease at any age.

CASE REPORTS: We report the diagnosis of cystic fibrosis in three adults within the same family. A 39 yr old man, was diagnosed with congenital absence of the vas deferens; the diagnosis of cystic fibrosis was achieved based on a positive chloride sweat test and the identification of two mutations in the CFTR gene. His mother experienced repeated bronchial infections that began when she was 12 years old. The diagnosis of cystic fibrosis was considered at the age of 74 yr after her son was diagnosed with this disease. Sweat test showed normal chloride concentrations and cystic fibrosis was suspected based on elevated basal transepithelial nasal potential difference. Genetic testing for the 33 most frequent mutations in the CFTR gene showed only one mutation. A second rare mutation was identified by complete sequencing of the CFTR gene, confirming the diagnosis of cystic fibrosis. A third case of pauci-symptomatic cystic fibrosis was diagnosed in a brother of the index case.

CONCLUSION

These observations illustrate the challenge of diagnosing milder forms of cystic fibrosis in adult subjects. The recognition of this diagnosis may lead to improvement in patient's care and to genetic counselling.