CPT® Code 81171

AFF2 (ALF transcription elongation factor 2 [FMR2]) (eg, fragile X intellectual disability 2 [FRAXE]) gene analysis; evaluation to detect abnormal (eg, expanded) alleles

The CPT® Code 81171 pertains to the molecular genetic testing of the AFF2 gene, which is also known as the AF4/FMR2 family, member 2 (FMR2) gene. This analysis is specifically designed to evaluate and detect abnormal alleles, particularly those that are expanded, which are associated with fragile X intellectual disability 2 (FRAXE). The procedure is crucial for identifying mutations that can lead to fragile X mental retardation syndrome, a condition characterized by a range of developmental issues including developmental delays, autism spectrum disorder (ASD), intellectual disabilities, learning difficulties, communication deficits, attention problems, and hyperactivity. The AFF2 gene is located on the long arm of the X chromosome at position Xq28 and plays a significant role in coding a protein that regulates mRNA blueprints necessary for protein binding within the cell nucleus. In individuals with fragile X mental retardation, there is a notable mutation characterized by an expansion of the CGG (cytosine-guanine-guanine) trinucleotide repeats within the AFF2 gene, which results in the silencing of gene expression. The analysis can reveal various statuses of the CGG repeats, including normal, intermediate, pre-mutation (carrier), and full mutation, with normal ranges typically falling between 4 to 40 repeats, while FRAXE conditions usually exhibit greater than 200 repeats. The code 81171 is specifically utilized to report the evaluation of the AFF2 gene to detect these abnormal, expanded alleles.