CBAVD is commonly associated with mutations in which gene?

• A. CFTR
• B. BRCA1
• C. FMR1
• D. HBB

Answer: (A)

CBAVD, or congenital bilateral absence of the vas deferens, is most strongly linked to mutations in CFTR, the cystic fibrosis transmembrane conductance regulator gene. CFTR encodes a chloride channel important for fluid secretion in many tissues. When CFTR function is altered by mutations, it can disrupt the development of the male reproductive tract, leading to the vas deferens being absent or underdeveloped, which causes obstructive azoospermia. Many men with CBAVD carry CFTR mutations, even if they don’t have classic cystic fibrosis symptoms, so genetic testing for CFTR is a key part of evaluation and informs reproductive planning.

The other genes listed are not associated with CBAVD. BRCA1 is tied to hereditary breast and ovarian cancer risk, FMR1 is related to fragile X conditions and certain fertility issues, and HBB relates to hemoglobinopathies like sickle cell disease.