Each patient underwent a complete diagnostic work-up, including physical examination, semen analysis (at least two samples), hormone analysis (follicle stimulating hormone, luteinizing hormone, prolactin, testosterone, inhibin-B), genetic testing (karyotype, Y-chromosome microdeletions, cystic fibrosis transmembrane conductance regulator gene /CFTR/testing), ultrasound (testis consistency and volume), microbiological testing (ejaculate, urethral smear; hepatitis, HIV), and other relevant examinations. The gene discussed is CFTR; the disease is Hepatitis.