CPT® Code 81282

Deleted

Long QT syndrome gene analyses (eg, KCNQ1, KCNH2, SCN5A, KCNE1, KCNE2, KCNJ2, CACNA1C, CAV3, SCN4B, AKAP, SNTA1, and ANK2); duplication/deletion variants

Molecular genetic testing is a critical process used to identify specific gene mutations that are responsible for long QT syndrome (LQTS). Long QT syndrome is a rare, inherited cardiac condition characterized by delayed repolarization of the heart, which can lead to serious complications. This condition is particularly sensitive to adrenergic stimulation, which can occur during activities such as exercise or excitement. The mutations associated with LQTS prolong the duration of the ventricular action potential, resulting in an extended QT interval on an electrocardiogram (ECG). Individuals diagnosed with LQTS face an increased risk of developing irregular heart rhythms, experiencing cardiac palpitations, suffering syncopal episodes (fainting), and even facing sudden death due to ventricular fibrillation. The genetic mutations linked to LQTS can be inherited in an autosomal recessive or dominant manner. More severe recessive phenotypes may also present with additional physical anomalies, such as syndactyly (fused fingers or toes) and/or congenital neural deafness. The testing process includes a full sequence analysis, which compares segments of genes to identify similarities or differences and to establish relationships among them. This analysis examines intrinsic features to locate active sites for post-translational modifications, as well as the structures of genes, including the distribution of introns, exons, and regulatory elements. Genetic markers are identified through the detection of point mutations or single nucleotide polymorphisms (SNPs). The most prevalent mutation associated with LQTS, known as LQT1, is located on the KCNQ1 gene found on chromosome 11 and is present in approximately 30-35% of individuals diagnosed with this syndrome. In cases where a familial variant has been identified, it is recommended that all first-degree relatives undergo molecular genetic testing to assess their risk factors. This genetic mapping can reveal common or familial variants among blood relatives. Specifically, CPT® Code 81282 pertains to the analysis of deletion and duplication variants in the genes associated with LQTS. A normal gene typically has two copies per cell, with exceptions for sex chromosomes; thus, the presence of zero or one copy indicates a deletion variant, while three or more copies suggest a duplication variant. Notably, the genes KCNH2 and SCN5A have been recognized as associated with these types of variants, which can also involve substitutions or changes in the amino acid sequencing of the gene.