DSG2 mutations contribute to arrhythmogenic right ventricular dysplasia/cardiomyopathy

Abstract

Arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C) is a disorder characterized by fibrofatty replacement of cardiac myocytes that typically manifests in the right ventricle. It is inherited as an autosomal dominant disease with reduced penetrance, although autosomal recessive forms of the disease also occur. We identified four probands with ARVD/C caused by mutations in DSG2, which encodes desmoglein-2, a component of the cardiac desmosome. No association between mutations in this gene and human disease has been reported elsewhere. One of these probands has compound-heterozygous mutations in DSG2, and the remaining three have isolated heterozygous missense mutations, each disrupting known functional components of desmoglein-2. We report that mutations in DSG2 contribute to the development of ARVD/C.

Figure 1.

Pedigrees and chromatograms demonstrating mutations in DSG2 for four probands with ARVD/C. In each pair of chromatograms, the top panel is from an unaffected control and the bottom panel is from the affected individual. A, Family A: individual A.III-1 with heterozygous R45Q (134G→A) mutation. B, Family B: individual B.II-1 with heterozygous R48H (143G→A) mutation and heterozygous W305X (915G→A) mutation. C, Family C: individual C.II-1 with heterozygous C506Y (1517G→A) mutation. D, Family D: individual D.II-4 with heterozygous G811C (2431G→T) mutation. Sequence analyses were performed bidirectionally with an ABI 3730 DNA Analyzer (Applied Biosystems). Chromatograms were analyzed using Sequencher 4.1 software for mutational analysis and with MacVector 7.2.2 software for ClustalW alignment. For pedigrees, squares represent males, circles represent females, blackened symbols indicate affected status, unblackened symbols indicate unaffected status, striped symbols indicate subdiagnostic features of ARVD/C, arrowheads indicate probands, dots indicate mutation carrier(s), and an asterisk (*) indicates that no DNA was available for sequencing.

Figure 2.

Location and conservation of mutated residues. A, Location of mutations along schematic representation of pre-pro-desmoglein-2. SS = signal peptide sequence; Pro = propeptide; TM = transmembrane domain; IA = intracellular anchor; IPL = intracellular proline-rich linker; RUD = repeated-unit domains; DTD = desmoglein-specific terminal domain (adapted from the work of Getsios et al.18). B, ClustalW sequence alignment of human DSG2 to orthologues and to other human desmogleins (DSG1, DSG3, and DSG4) and desmocollins (DSC2, DSC3,and DSC4). Identical residues are shaded in black; conserved residues are shaded in gray. Mutations identified in the present study are shown at the top of each alignment. The furin-recognition motif and plakoglobin binding domain are indicated.

Figure 3.

Compound heterozygous mutations in DSG2 for individual B.II-1. Total RNA was isolated from Epstein-Barr virus–transformed lymphoblasts from individual B.II-1 (Trizol [Invitrogen]; RNeasy clean-up [Qiagen]), and cDNA was generated by reverse transcription (Superscript III 1st-strand cDNA synthesis kit [Invitrogen]). PCR products amplified with primers spanning the proband’s two mutations were cloned into the pCR2.1 plasmid (TOPO-TA cloning kit [Invitrogen]), and several individual clones were sequenced using both M13 forward and reverse primers. Representative chromatograms from two clones are displayed, which demonstrate that the R48H and W305X mutations lie on different alleles.