Cystic Fibrosis Birth Incidence in Brittany Drops 50% Over 50 Years

The birth incidence of cystic fibrosis in Brittany decreased by 50.1% between the 1975–84 and 2015–24 decades, according to a study.

Researchers tracking people born with the condition between 1975 and 2024 found that the rate shifted from 1 in 2,175 to 1 in 4,361, with a clear breakpoint observed from the 1990s. The study examined temporal and spatial trends in cystic fibrosis birth incidence over 50 years in western France, focusing on 599 patients.

Patients born before the early implementation of newborn screening for cystic fibrosis in 1989 were recorded by combining data sources, while others were identified from the screening program.

The research notes a decline in birth incidence over the past 50 years, with a breakpoint coinciding with the availability of prenatal diagnosis. The analysis shows that cystic fibrosis—one of the most common rare genetic diseases—has changed considerably due to advances in disease care, widespread newborn screening, and the recent emergence of highly effective CFTR modulator therapies.

The study also revealed that a west-to-east gradient previously observed in Brittany strengthened over the study period. During the last decade, from 2015 to 2024, western Brittany exhibited a birth incidence rate 84.9% higher than that of eastern Brittany, recording 1 in 3,120 compared to 1 in 5,769. Researchers said that this higher incidence occurs in western Brittany, a peninsula with lower population mixing.

No upward trend has yet been observed since the expansion of access to elexacaftor/tezacaftor/ivacaftor (ETI) therapy in France, and ongoing monitoring remains essential to assess the potential effect of the recent advent of CFTR modulator therapies.