CPT® Code 81224

CFTR (cystic fibrosis transmembrane conductance regulator) (eg, cystic fibrosis) gene analysis; intron 8 poly-T analysis (eg, male infertility)

Molecular genetic testing is a critical diagnostic tool used to identify specific mutations in the CFTR gene, which is located on chromosome 7. This gene is responsible for encoding the cystic fibrosis transmembrane conductance regulator protein, which plays a vital role in the regulation of salt and water transport across epithelial cell membranes. Mutations in the CFTR gene are primarily associated with cystic fibrosis (CF), a genetic disorder that affects the respiratory, digestive, and reproductive systems. Additionally, these mutations can lead to congenital bilateral absence of the vas deferens (CBAVD), a condition that can result in male infertility. The testing process involves analyzing the gene for specific mutations, particularly focusing on the intron 8 poly-T region, which is crucial for understanding the genetic basis of these conditions. Males presenting with symptoms such as azoospermia (absence of sperm in semen), low semen ejaculatory volume, and the absence of the vas deferens as observed through clinical examination or ultrasound are considered suitable candidates for this molecular genetic testing. The intron 8 poly-T analysis serves as a reflex test that is conducted when a known disease-causing mutation, such as the R117H mutation, is detected. This analysis evaluates the poly-T tract, which consists of a series of thymidine bases and has three common variants: 5T, which is associated with a penetrant mutation, and 7T and 9T, which are classified as polymorphic variants. Understanding these genetic variations is essential for accurate diagnosis and management of conditions related to CFTR gene mutations.