Missense variants in plakophilin-2 in arrhythmogenic right ventricular cardiomyopathy patients--disease-causing or innocent bystanders?
OBJECTIVE
Mutations in genes encoding desmosomal proteins have been linked to arrhythmogenic right ventricular cardiomyopathy/dysplasia (ARVC/D). We hypothesized that a Scandinavian ARVC/D population would have a different spectrum of plakophilin-2 (PKP2) mutations and that some of the reported missense mutations may not be pathogenic.


METHODS
We screened 53 unrelated patients fulfilling Task Force criteria for ARVC/D for mutations in PKP2 by direct sequencing.


RESULTS
Seven different mutations were identified: two insertion/deletions (E329fsX352, P401fsX406), 1 splice site (2146-2A>T), 1 non-sense (R79X) and 4 missense mutations (Q62K in 2 patients, G489R, G673V) of undeterminable pathogeneity. None of these mutations was present in 650 controls. Five of the mutations were novel. Seven patients carried reported missense mutations (D26N, S140F, V587I); however, these mutations were identified in our healthy controls, although at a lower frequency. Evaluation of all reported missense mutations in PKP2 showed unclear pathogeneity of several reported mutations.


CONCLUSIONS
Fifteen percent of Danish ARVC/D patients carried PKP2 mutations. Our finding of reported disease-causing mutations at a low frequency among healthy controls suggests that these variants are disease modifying but not directly disease causing. We recommend conservative interpretation of missense variants in PKP2, functional characterization and large-scale sequencing to clarify normal variation in the gene.
Christensen
Alex Hørby
AH
Department of Cardiology, Rigshospitalet, Copenhagen University Hospital, Copenhagen, Denmark.
Benn
Marianne
M
Tybjaerg-Hansen
Anne
A
Haunso
Stig
S
Svendsen
Jesper Hastrup
JH
D019571:Arrhythmogenic Right Ventricular Dysplasia / Q000235:genetics*; D016022:Case-Control Studies; D017124:Conserved Sequence; D003718:Denmark; D019143:Evolution, Molecular; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D020125:Mutation, Missense; D010641:Phenotype; D051191:Plakophilins / Q000235:genetics*; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA
C495337:PKP2 protein, human; D051191:Plakophilins