A Case of Cystic Fibrosis in a Japanese Man With Congenital Bilateral Absence of the Vas Deferens and Recurrent Pancreatitis Caused by a Homozygous c.1210-11 T > G Variant of the Cystic Fibrosis Transmembrane Conductance Regulator Gene.

Case: We herein report a rare case of a Japanese man diagnosed with cystic fibrosis (CF) following a workup for male infertility and recurrent pancreatitis and discuss the clinical and diagnostic implications in a population wherein CF is exceptionally rare. A 27-year-old Japanese man who presented with azoospermia underwent clinical evaluation, imaging, and genetic testing. The patient, who had a history of recurrent pancreatitis, was subsequently diagnosed with congenital bilateral absence of the vas deferens (CBAVD). Outcome: Genetic analysis identified a homozygous c.1210-11 T > G variant in the cystic fibrosis transmembrane conductance regulator (CFTR) gene. This variant is classified as pathogenic and is associated with variable clinical phenotypes. Combined with the clinical symptoms, the patient was diagnosed with CF. Spermatozoa were successfully retrieved via testicular sperm extraction for future use in intracytoplasmic sperm injection. A literature review was also conducted to contextualize the genetic findings. Conclusion: We report a rare case of CF caused by a homozygous c.1210-11 T > G CFTR variant in a Japanese individual. This case highlights that CFTR-RD, while rare, should be considered in Japanese patients presenting with CBAVD or idiopathic pancreatitis.