AIMS: To investigate whether phospholamban gene (PLN) mutations underlie 
patients diagnosed with either arrhythmogenic right ventricular cardiomyopathy 
(ARVC) or idiopathic dilated cardiomyopathy (DCM).
METHODS AND RESULTS: We screened a cohort of 97 ARVC and 257 DCM unrelated index 
patients for PLN mutations and evaluated their clinical characteristics. PLN 
mutation R14del was identified in 12 (12 %) ARVC patients and in 39 (15 %) DCM 
patients. Haplotype analysis revealed a common founder, estimated to be between 
575 and 825 years old. A low voltage electrocardiogram was present in 46 % of 
R14del carriers. Compared with R14del- DCM patients, R14del+ DCM patients more 
often demonstrated appropriate implantable cardioverter defibrillator discharge 
(47 % vs. 10 % , P < 0.001), cardiac transplantation (18 % vs. 2 % , P < 0.001), 
and a family history for sudden cardiac death (SCD) at < 50 years (36 % vs. 16 % 
, P = 0.007). We observed a similar pattern in the ARVC patients although this 
was not statistically significant. The average age of 26 family members who died 
of SCD was 37.7 years. Immunohistochemistry in available myocardial samples 
revealed absent/depressed plakoglobin levels at intercalated disks in five of 
seven (71 %) R14del+ ARVC samples, but in only one of nine (11 %) R14del+ DCM 
samples (P = 0.03).
CONCLUSIONS: The PLN R14del founder mutation is present in a substantial number 
of patients clinically diagnosed with DCM or ARVC. R14del+ patients diagnosed 
with DCM showed an arrhythmogenic phenotype, and SCD at young age can be the 
presenting symptom. These findings support the concept of 'arrhythmogenic 
cardiomyopathy'.