Combating Diagnostic Wandering and Impasse for Cystic Fibrosis

After cystic fibrosis (CF) neonatal screening, some children remain with a not concluded diagnosis. In France, the medical follow-up is not standardized, some of them may be lost of follow-up. The aim of the study is to identify children at risk of developing CF. Other children carry mutation at risk of CFTR related disorder (CFTR-RD) but remain asymptomatic during childhood. The aim of the study is to evaluate those children by microbiology, respiratory function test and lung imaging tests to reclassify them in the CFTR spectrum.

Inclusion Criteria:undiagnosed patients with hypertrypsinemia at CF neonatal screening and :either an intermediate chloride sweat test (30-59 mmol/L) and at most one CFTR mutationor negative chloride sweat test (< 30 mmol/L) and two CFTR mutations one of wich is of unknown significance (VUS)patients with two CFTR mutations at least one of which is of Varying Clinical Consequence according to "CFTR2" database or "CFTR-RD" according to "CFTR-France" database.Exclusion Criteria:CF patients with 2 CF causing mutations