Abstract
Aim: We aimed to compare the clinical and laboratory features of siblings with cystic fibrosis (CF) registered in the Cystic Fibrosis Registry of Turkiye (CFRT-TR) in 2023, both before and after newborn screening (NBS) and modulatory treatment. Method: Siblings with two or more CF diagnoses were included. A comparison was made based on clinical and laboratory characteristics before and after NBS (before 2015) and modulatory treatment. Results: A total of 240 siblings from 113 families were included (47% female), with a mean age of 9 years. The median age at diagnosis was 0.33 years. Of these, 135 were born before NBS. Among those not receiving modulatory treatment, the mean age of diagnosis for older siblings was (2.97±4.36 years), compared to (1.00±2.29 years) for younger siblings (p<0.001). No significant differences in weight, height, BMI z-scores, colonization status, or FEV1% were found between older and younger siblings (p>0.05), though liver disease was more common in older siblings (p=0.011). Younger siblings diagnosed after NBS were diagnosed earlier (0.59±1.10 years) than older siblings diagnosed before NBS (2.84±4.37 years) (p=0.003). No significant differences in clinical parameters were found between the two groups (p>0.05). No differences were noted in FEV1 changes, growth parameters, colonization status, or complications before and after modulatory treatment between the older and younger siblings. Conclusions: Younger siblings were diagnosed earlier with NBS. Having more than two CF siblings did not affect clinical follow-up. Modulatory treatment improved clinical and laboratory outcomes, consistent with existing CF literature.