BACKGROUND: Prenatal therapy with elexacaftor/tezacaftor/ivacaftor (ETI) has recently emerged as a potential strategy to modify the early natural history of cystic fibrosis (CF). While case reports have described prevention of meconium ileus and pancreatic insufficiency, data on male reproductive outcomes remain extremely limited. CASE PRESENTATION: We report a male infant with CF (homozygous F508del) whose heterozygous carrier mother initiated ETI at 27+4 weeks of gestation after prenatal diagnosis. Pregnancy was uneventful until preterm delivery at 35+2 weeks. The neonate presented with normal meconium passage, persistently normal fecal elastase, and no pulmonary abnormalities on magnetic resonance imaging. ETI was initiated directly in the infant at day 11 of life, with subsequent catch-up growth and discontinuation of pancreatic enzyme replacement therapy at 8 weeks. Remarkably, ultrasound at 8 weeks demonstrated bilateral vas deferens, a structure typically absent in nearly all male patients with CF at birth. Sweat chloride concentrations normalized under therapy, and no CF-typical manifestations were observed during the first 7 months of life. CONCLUSION: This is the first report of a male infant with CF in whom prenatal ETI via a heterozygous carrier mother, started in the second trimester and continued postnatally, was associated with preserved exocrine pancreatic function, absence of pulmonary disease, and presence of vas deferens. These findings suggest that prenatal CFTR modulation - even when initiated late in gestation - may alter the trajectory of CF-related organ manifestations, including male reproductive development. Long-term follow-up is essential to determine whether these early benefits translate into sustained preservation of fertility and multiorgan function.
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