CPT® Code 81274

The CPT® Code 81274 pertains to the molecular genetic testing of the HTT (huntingtin) gene, specifically focusing on the characterization of alleles associated with Huntington disease. Huntington disease is a progressive neurodegenerative disorder that significantly impacts cognitive and motor functions. The HTT gene, located on the short arm of chromosome 4 at position 16.3 (4p16.3), encodes a protein that plays a crucial role in the functioning of nerve cells, which is essential for normal brain development. This gene is involved in various cellular processes, including chemical signaling, protein binding, and cellular protection against self-destruction. The testing performed under this code aims to identify abnormal or expanded alleles of the HTT gene, which are linked to the onset and progression of Huntington disease. The gene features a specific DNA sequence characterized by a trinucleotide repeat pattern of cytosine, adenine, and guanine (CAG), which typically repeats between 10 to 35 times in healthy individuals. However, when this repeat expands beyond the normal range, it can lead to the production of an elongated protein that is prone to fragmentation and accumulation within nerve cells, contributing to the symptoms of the disease. Symptoms of Huntington disease can manifest as cognitive decline, dementia, apathy, depression, anxiety, and involuntary movements, with onset varying from childhood or adolescence in juvenile cases to mid-adulthood in typical cases. The testing provided by CPT® Code 81274 is essential for determining the characteristics of these expanded alleles, including their size and any similarities or differences that may exist among them. This information is critical for understanding the genetic basis of the disease and for assessing the risk of transmission to future generations.