CPT® Code 81204

AR (androgen receptor) (eg, spinal and bulbar muscular atrophy, Kennedy disease, X chromosome inactivation) gene analysis; characterization of alleles (eg, expanded size or methylation status)

The CPT® Code 81204 pertains to the molecular genetic testing of the AR (androgen receptor) gene, which is crucial for identifying mutations associated with various conditions, including androgen inactivation syndrome, spinal and bulbar muscular dystrophy, Kennedy disease, androgenetic alopecia, and polycystic ovarian syndrome. The AR gene is situated on the long (q) arm of the X chromosome at position 12 (Xq12) and plays a vital role in the development of male characteristics by encoding a protein that binds to androgen hormones, such as testosterone. This binding process is essential for regulating the development of male traits during both gestation and puberty. The normal function of the AR gene involves a specific trinucleotide repeat of CAG (cytosine-adenine-guanine), which typically ranges from fewer than 10 to about 36 repeats. However, in conditions like spinal and bulbar muscular dystrophy, the number of CAG repeats can increase significantly, ranging from 38 to over 60. This increase is associated with symptoms such as progressive muscle wasting, gynecomastia, testicular atrophy, and fertility issues, predominantly affecting males aged 30 to 60. Mutations in the AR gene can lead to androgen insensitivity syndrome, which results in male feminization due to various genetic alterations, including single base pair changes or insertions and deletions of multiple base pairs. Additionally, in androgenetic alopecia, mutations typically involve minor changes in the base pairs, leading to characteristic hair loss in both males and females. Women with alterations in the AR gene may also experience symptoms of polycystic ovarian syndrome, such as hirsutism, acne, and fertility challenges. The code 81204 specifically reports on the characterization of alleles, including expanded size or methylation status, providing essential insights into these genetic conditions.