CPT® Code 81180

ATXN3 (ataxin 3) (eg, spinocerebellar ataxia, Machado-Joseph disease) gene analysis, evaluation to detect abnormal (eg, expanded) alleles

Molecular genetic testing is a critical procedure used to identify mutations in specific genes associated with various genetic disorders. In the case of CPT® Code 81180, the focus is on the ATXN3 (ataxin 3) gene, which is linked to spinocerebellar ataxia (SCA), particularly the most prevalent form known as Machado-Joseph disease. Spinocerebellar ataxia is characterized as a slowly progressive degenerative condition affecting the cerebellum and spinal cord, leading to a range of neurological symptoms. These symptoms can vary significantly based on which gene carries the mutation, but they often include uncoordinated gait (ataxia), muscle stiffness or spasms, tremors, and difficulties with speech (dysarthria) and swallowing (dysphagia). Additional manifestations may involve problems with hand-eye coordination, involuntary eye movements (nystagmus), vision issues, sleep disturbances, and challenges with learning, processing information, and memory retention. The ATXN3 gene is located on the long (q) arm of chromosome 14 at position 32.12 (14q32.12) and encodes an enzyme protein that plays a vital role in the ubiquitin proteasome system, which is responsible for the degradation and removal of damaged proteins from the body. In individuals with SCA3, the ATXN3 gene exhibits a unique DNA allele characterized by a trinucleotide repeat pattern of CAG (cytosine-adenine-guanine), which typically repeats fewer than 50 times. However, in cases of SCA3, this repeat expands to more than 50 times, leading to the associated symptoms of the disease. The onset of symptoms can occur at any age, from childhood to late adulthood, but they most commonly present during mid-adulthood. The CPT® Code 81180 specifically reports the analysis of the ATXN3 gene to evaluate and detect these abnormal (expanded) alleles, facilitating the diagnosis and understanding of the genetic basis of the condition.