Desmosomal mutations across the fence

Abstract

t w s I Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is predominantly an autosomal-dominant disease with variable penetrance and expression. ARVD/C in its classic form affects the right ventricle, but patients could also have predominantly the left ventricle involved and in many cases biventricular involvement. Patients are susceptible to developing ventricular arrhythmias and related consequences. The genetic pathology of ARVD/C is found in the genes encoding for desmosomal proteins, including plakoglobin (JUP), plakophilin-2 (PKP2), desmoglein-2 (DSG2), desmocollin-2 (DSC2), desmoplakin (DSP) and desmin (Des). Mutations in all of these genes comprise 30% to 50% of the ARVD/C patients, and 90% of all the mutations are located in PKP2. TMEM43 is the only gene in which a mutation was reported to cause fully penetrant and lethal ARVD/C phenotype. Functionally, muations in any of these desmosomal genes could lead to RVD/C by jeopardizing the integrity of the cellular archiecture. In this issue of the Journal, Lahtinen et al report on the presence of desmosomal mutations in Finland. They have screened 29 Finnish ARVD/C probands for mutations in the PKP2, DSP, DSG2, and DSC2 genes. A total of 5 mutations (3 PKP2, 1 DSG2, 1 DSP) were detected in their probands. Then, they searched for these 5 mutations in 6,334 Finnish individuals. These control individuals had undergone extensive health-related questionnaire and clinical examinations, including electrocardiograms. Disease-related PKP2 mutations were found in 25 of these healthy individuals followed by DSP in 5 subjects and DSG2 mutations in 1. Altogether, it seems that 1 in 200 average individuals in Finland are carriers of an ARVD/C-related mutation, which is an extraordinarily high prevalence at a first glance. Digging further into the health questionnaire and clinical examination dossiers, 6 of the PKP2 mutation carrier control subjects had self-reported arrhythmia and 1 carrier showed frequent premature ventricular complexes of left bundle branch block morphology. Further, the QT interval was found to be