CPT® Code 81332

SERPINA1 (serpin peptidase inhibitor, clade A, alpha-1 antiproteinase, antitrypsin, member 1) (eg, alpha-1-antitrypsin deficiency), gene analysis, common variants (eg, *S and *Z)

The CPT® Code 81332 refers to a molecular genetic test that analyzes the SERPINA1 gene, which is crucial for producing the protein alpha-1 antitrypsin (AAT). This protein functions as a serine protease inhibitor, meaning it helps regulate chemical reactions in the body by inhibiting specific enzymes. AAT is primarily synthesized in the liver and is transported through the bloodstream to the lungs, where it plays a vital role in protecting lung tissue from damage caused by enzymes such as neutrophil elastase. In cases where there is a deficiency of AAT, neutrophil elastase can become overly active, leading to the destruction of alveoli, the small air sacs in the lungs, which can result in emphysema. The SERPINA1 gene is located on chromosome 14 and has been associated with over 120 identified mutations, most of which alter the gene's molecular structure by substituting one amino acid for another. The two most prevalent variants of this gene are the 'S' allele, which alters glutamic acid to valine at codon 264, and the 'Z' allele, commonly found in individuals of North Western European descent, which changes glutamic acid to lysine at position 342. In addition to causing AAT deficiency, certain mutations can lead to abnormal binding of AAT, resulting in a large molecule that accumulates in the liver, potentially causing liver damage, while also leaving the lungs vulnerable to damage from neutrophil elastase. Alternatively, some mutations may produce a smaller AAT molecule that is rapidly degraded by the liver, preventing it from reaching the lungs and providing necessary protection, thereby increasing the risk of emphysema. Molecular genetic testing for SERPINA1 is indicated for individuals exhibiting symptoms related to alpha-1 antitrypsin deficiency or those with a family history of the condition.