Phenotypic Analysis of Arrhythmogenic Cardiomyopathy in the Hutterite Population: Role of Electrocardiogram in Identifying High‐Risk Desmocollin‐2 Carriers

BACKGROUND: The p.Gln554X mutation in desmocollin-2 (DSC2) is prevalent in ≈10% of the Hutterite population. While the homozygous mutation causes severe biventricular arrhythmogenic right ventricular cardiomyopathy, the phenotypic features and prognosis of heterozygotes remain incompletely understood. METHODS AND RESULTS: Eleven homozygotes (mean age 32±8 years, 45% female), 28 heterozygotes (mean age 40±15 years, 50% female), and 22 mutation-negatives (mean age 43±17 years, 41% female) were examined. Diagnostic testing was performed as per the arrhythmogenic right ventricular cardiomyopathy modified Task Force Criteria. Inverted T waves in the right precordial leads on ECG were seen in all homozygotes but not in their counterparts (P<0.001). Homozygotes had higher median daily premature ventricular complex burden than did heterozygotes or mutation-negatives (1407 [IQR 1080 to 2936] versus 2 [IQR 0 to 6] versus 6 [IQR 0 to 214], P=0.0002). Ventricular tachycardia was observed in 60% of homozygotes but in none of the remaining individuals (P<0.001). On cardiac magnetic resonance imaging, homozygotes had significantly larger indexed end-diastolic volumes (right ventricular: 122±24 versus 83±17 versus 83±12 mL/m(2), P<0.0001; left ventricular: 93±18 versus 76±13 versus 80±11 mL/m(2), P=0.0124) and lower ejection fraction values compared with heterozygotes and mutation-negatives (right ventricular ejection fraction: 41±9% versus 59±9% versus 61±6%, P<0.0001; left ventricular ejection fraction: 53±8% versus 65±5% versus 64±5%, P<0.0001). Most affected individuals lacked right ventricular wall motion abnormalities. Thus, few met cardiac magnetic resonance imaging task force criteria. CONCLUSIONS: The ECG reliably identifies homozygous p.Gln554X carriers and may be useful as an initial step in the screening of high-risk Hutterites. The cardiac phenotype of heterozygotes appears benign, but further prospective follow-up of their arrhythmic risk is needed.