CPT® Code 81177

ATN1 (atrophin 1) (eg, dentatorubral-pallidoluysian atrophy) gene analysis, evaluation to detect abnormal (eg, expanded) alleles

The CPT® Code 81177 pertains to the molecular genetic testing specifically aimed at analyzing the ATN1 (atrophin 1) gene, which is associated with a condition known as dentatorubral-pallidoluysian atrophy (DRPLA). This gene is located on the short (p) arm of chromosome 12 at the position designated as 12p13.31. The primary function of the ATN1 gene is to provide the necessary instructions for the synthesis of the atrophin 1 protein. In individuals affected by DRPLA, there is an abnormal accumulation of this altered atrophin 1 protein within the brain, leading to the destruction of neurons and the subsequent development of the disease. The normal function of the ATN1 gene includes maintaining a specific range of trinucleotide CAG (cytosine-adenine-guanine) repeats, which typically ranges from 6 to about 35. However, in cases of DRPLA, the number of CAG repeats is significantly higher, often reaching 48 or more. This genetic mutation primarily affects individuals of Asian descent, with symptoms that can manifest at any age between 1 and 72 years, although the average age of onset is around 31 years. In children, the symptoms of DRPLA may include progressive ataxia, myoclonus, seizures, and intellectual deterioration. Adults may experience a different set of symptoms, including ataxia, choreoathetosis, dementia, and changes in personality. Management of these symptoms can involve the use of antiepileptic medications for seizure control, psychotropic drugs to address personality changes, and physical rehabilitation to assist with ataxia, myoclonus, and choreoathetosis. The code 81177 is specifically utilized to report the analysis of the ATN1 gene for the purpose of evaluating and detecting these abnormal (expanded) alleles associated with DRPLA.