CPT® Code 81200

The CPT® Code 81200 pertains to the molecular genetic testing of the ASPA (aspartoacylase) gene, specifically focusing on the analysis of common variants associated with Canavan disease. Canavan disease is a genetic disorder that is inherited in an autosomal recessive manner, meaning that an individual must inherit two copies of the mutated gene—one from each parent—to manifest the disease. Those who inherit only one mutated copy become carriers but do not exhibit symptoms. This condition predominantly affects individuals of Ashkenazi Jewish descent, highlighting the importance of genetic testing in this population. The ASPA gene plays a crucial role in producing the enzyme aspartoacylase, which is essential for the breakdown of N-acetyl-L-aspartic acid (NAA) in the brain. NAA is believed to be vital for the maintenance of white matter, which consists of nerve fibers insulated with myelin. Mutations in the ASPA gene can severely impair the function of aspartoacylase, leading to a reduction or complete loss of its enzymatic activity. This impairment results in the accumulation of NAA and subsequent deterioration of white matter, which is critical for proper neurological function. Among the more than 55 known mutations of the ASPA gene, the E285A and Y231X variants are the most prevalent. The E285A mutation alters the enzyme's structure by substituting glutamic acid with alanine, while the Y231X mutation leads to a premature stop in protein synthesis, resulting in a nonfunctional enzyme. Genetic testing for these mutations is essential for identifying carriers and diagnosing individuals with Canavan disease, which significantly impacts various aspects of infant development, including motor skills, feeding, and cognitive abilities. Tragically, most affected individuals do not survive past 18 months, although some may live into their teenage years or early adulthood if they have a milder form of the disease.