Cystic fibrosis diagnosis in adulthood as a result of study of relatives within the newborn screening programme

Introduction: Newborn screening (NS) for cystic fibrosis (CF) provides the opportunity for cascade carrier testing of relatives when a positive case is discovered. In our Center NS was implemented 16 years ago. Routinely all parents of a cf newborn are tested to confirm carrier diagnosis. Objective: to describe our experience in diagnosis of CF in parents of children with CF discovered through NS. Methods: We examined clinical retrospective data of parents of children diagnosed with CF through NS. Results: 100 children with CF were detected by NS in our Center. All couples were genetically studied to be confirmed as carriers. All parents were identified as heterozygous carriers of the corresponding mutation with the exception of three parents whom in addition to the corresponding mutation presented other CFTR mutations in trans . Case 1: Sweat test (ST)= 65 mmol/L and genotype F508del/ D443Y, G576A, R668C; Case 2: ST= 69Mmol/L and genotype G576A, R668C/ 5T-12TG; Case 3: the index case showed a genotype F508del/ F587I. Genetic testing of the mother identified the same mutation as her affected son. She transmitted the F587I mutation and the F508del was transmitted from the father. Her ST was 75 mmol/l. All 3 parents had normal pulmonary function test, clinical symptoms (rhinosinusitis and bronchitis)were presented and in 2 males conception of the CF baby through in vitro fertilization make suspicion of CF diagnosis that was lately confirmed by genetic testing. Conclusions: Carrier testing after a CF diagnosis through NS should be mandatory in order to identify true carriers or mild CF cases for follow-up and familial genetic counselling.