Initial Regional Evaluation of Cystic Fibrosis Newborn Screening Program: Data from Mediterranean Coast of Turkey.

Background/ aim: Since January 2015, Cystic Fibrosis Newborn Screening (CFNS) program has been implemented in Turkey. We aimed to evaluate the demographic, clinical and laboratory data of cases referred from the CFNS program, and to determine the most suitable cut-off value for immunoreactive trypsinogen (IRT)-1 and immunoreactive trypsinogen (IRT-2) that are used in CFNS program in Turkey.A total of 156 Turkish-Caucasian subjects were determined as positive cases during 3 years, January 2015-January 2018, and were referred to the Pediatric Pulmonology clinics of Akdeniz University Hospital, Antalya, Turkey, national CFNS program. The evaluation was made considering the IRT-1, IRT-2 values, demographic characteristics, sweat test results, CFTR genotypes, and diagnoses.Nine cases were diagnosed with Cystic Fibrosis (CF). Eight cases were diagnosed with CF-related metabolic syndromes and three cases were determined as CF carriers. The ratio of CF to CF-related metabolic syndrome was determined as 1.1:1. Considering the limits of the present CFNS program and IRT method, the Positive Predictive Value (PPV) for the referred cases was determined as 5.8%. When a cut-off value of 105.6 ng/ml was taken for IRT-1, sensitivity was 100%, specificity was 59% and PPV was 12.8%. For a cutoff value of 88.75 ng/ml for IRT-2, sensitivity was determined as 90%, specificity as 65% and PPV as 15.2%.This is the first detailed clinical study that has evaluated the data from the CFNS program in the Mediterranean coast of Turkey. As false positive results are extremely high in Turkey, there is an urgent need for revision of IRT-1 and IRT-2 limits by evaluating the data of the whole country.