Disease-associated Genetic Variants Common Among Those With Early-onset Afib, Study Finds

About 3% of patients with early-onset atrial fibrillation have a genetic mutation associated with hypertrophic cardiomyopathy (HCM), according to a recent study designed to answer questions about whether genetic testing ought to be incorporated into the care of early-onset atrial fibrillation.

For the purposes of this study, early-onset atrial fibrillation was defined as a diagnosis that made before people turned 66. The overall results of the research suggest that 1 in 10 of early-onset atrial fibrillation patients have a “disease-associated variant” for a cardiomyopathy (including other kinds, not just HCM) and inherited arrhythmia syndromes and that the chances increased as the age of diagnosis got younger (16.8% in those diagnosed before age 30).

Corresponding author M. Benjamin Shoemaker, M.D., M.S.C.I., of the Vanderbilt University Medical Center and his colleagues said their results support the use of genetic testing of early-onset atrial fibrillation patients. They reported their findings in JAMA Cardiology in September.

Shoemaker and his colleagues conducted whole genome sequencing of 1,293 early-onset atrial fibrillation who had enrolled in Vanderbilt patient registries related to atrial fibrillation. The panel they looked at was limited to 145 genes selected from cardiomyopathy and arrhythmia panels.

Gene variants associated with dilated cardiomyopathy were the most common: Shoemaker and his group found that 93 of the 1,293 patients (7.2%) had a variant associated dilated cardiomyopathy. The next most common variants were from HCM: 42 of the study population of 1,293, which works out to 3.3%. The third most common variants were for arrhythmogenic cardiomyopathy/arrhythmogenic right ventricular cardiomyopathy (AC/ARVC: 37 patients, or 2.9%.

When a stricter definition of the association between the variant and the disease was used (that is, the evidence of a connection was stronger) the numbers were, not surprisingly, smaller but the order of the prevalence was the same: 69 (5.3%) variants associated with dilated cardiomyopathy, 27 (2.1%) for HCM and just five (0.4%) for AC/ARVC.

The most common disease-associated mutations identified by the sequencing were loss-of-function variants in the TTN gene (27%). But next two most common were variants MYH7 (13%) and MYH6 genes, both of which encode myosin, a protein instrumental in heart muscle contraction.