Routine diagnostic work‐up for genetic causes of male infertility recommended in the Dutch and the European guidelines includes karyotyping and azoospermia factor (AZF) deletion screening for patients with extreme oligozoospermia or azoospermia, and screening for variants in the CFTR gene in case of (assumed) congenital bilateral absence of the vas deferens (CBAVD).5, 6. This evidence concerns the gene CFTR and male infertility.