Clinical, Genetic, and Epidemiological Characteristics of Ar-Rhythmogenic Cardiomyopathy Associated With the Pathogenic Founder Variant NP_00454563.2 (p.Glu259Glyfs*77) in Gene PKP2

Introduction and objectives: arrhythmogenic cardiomyopathy (ACM) is a hereditary heart disease defined by the progressive replacement of the ventricular myocardium with fibroadipose tissue, which can act as a substrate for arrhythmias, sudden death, or even give rise to heart failure (HF). Sudden death is frequently the first manifestation of the disease, particularly among young patients. The aim of this study is to describe a new pathogenic variant in the PKP2 gene. Methods: A descriptive observational study that included 8 initially non-interrelated families with a diagnosis of ACM undergoing follow-up at our HF and Familial Cardiomyopathies Unit, who were carriers of the NM_004572.3:c.775_776insG; p. (Glu259Glyfs*77) variant in PKP2 gene. The genetic testing employed next-generation sequencing for the index cases, and the Sanger method for the targeted study with family members. We compiled personal and family histories, demographic and clinical characteristics, data from the additional tests at the time of diagnosis, and arrhythmic events at diagnosis and during follow-up. Results: We included 47 subjects, of whom 8 were index cases (17%). Among the evaluated family members, 16 (34%) were carriers of the genetic variant, 3 of whom also had a diagnosis of ACM. The majority were women (26 patients; 55.3%), with a mean age on diagnosis of 48.9 ± 18.6 years, and a median follow-up of 39 [24-59] months. Worthy of note are the high incidence of arrhythmic events as the form of presentation and in follow-up (21.5% and 20.9% respectively), and the onset of HF in 25% of the sample. The most frequent ventricular involvements were right (4 patients 16.7%) and biventricular (4 patients 16.7%); we found no statistical differences in any of the variables analysed. Conclusions: This variant is a pathogenic variant of gene PKP2 that has not previously been described and is not present in the control groups associated with ACM. It has incomplete penetrance, a highly variable phenotypic expressivity, and was identified in 8 families of our geographical area in Malaga (Andalusia, Spain), where we can establish a founder effect and describe the clinical and risk characteristics.