CPT® Code 81289

The CPT® Code 81289 pertains to the molecular genetic testing of the FXN (frataxin) gene, which is associated with Friedreich ataxia, a progressive neuromuscular disorder characterized by a range of debilitating symptoms. The FXN gene is located on the long (q) arm of chromosome 9 at position 21.11 (9q21.11) and is responsible for coding a protein that plays a crucial role in iron metabolism, antioxidant protection, and energy production within the body. This protein is distributed throughout various tissues, with the highest concentrations found in the heart, spinal cord, liver, pancreas, and skeletal muscles. Friedreich ataxia manifests through a variety of symptoms, including impaired balance and coordination, decreased strength and sensation in the extremities, muscle stiffness and spasticity, as well as potential speech, hearing, and visual impairments. Additionally, individuals may experience hypertrophic cardiomyopathy, diabetes, and scoliosis. The onset of symptoms typically occurs between the ages of 5 and 15 in approximately 75% of cases, while the remaining 25% may not exhibit symptoms until after the age of 25. The FXN gene features a unique DNA allele characterized by a trinucleotide repeat pattern of three amino acids: glycine, alanine, and alanine (GAA), which usually repeats fewer than 33 times. Normal variations include short normal repeats of fewer than 12 and long normal repeats ranging from 12 to 33. Most individuals affected by Friedreich ataxia possess two homozygous genes with expanded trinucleotide repeats located on intron 1 of the FXN gene. A smaller percentage, about 2%, may have one gene with expanded repeats and another with a point mutation or deletion. The code 81289 specifically reports the analysis of the FXN gene to detect known familial variants, thereby facilitating the identification of at-risk family members when there is a documented family history of Friedreich ataxia. This targeted analysis focuses on specific sites within the FXN gene that have previously been identified as mutated in other family members.