0247 : Detection and prevalence of large PKP2 deletion in arrhythmogenic right ventricular cardiomyopathy using exome sequencing, qPCR and multiplex ligation-dependent probe amplification (MLPA®)

Abstract

Arrhythmogenic Right Ventricular Cardiomyopathy (ARVC) is an inherited heart muscle disease mainly caused by desmosomal gene mutations. PKP2 is the major ARVC causing-gene and presents frequent truncating mutations leading to haploinsufficiency. Large deletions of PKP2 , which are not detected with standard Sanger sequencing, have been reported in few ARVC patients. This study aimed to compare different screening methods for detection of large PKP2 deletions and to determine their prevalence in the ARVC population. We included 19 patients and 1 family of 4 members with a diagnosis of familial ARVC, which were screened negative by Sanger sequencing. A whole exome capture was performed with the Agilent SureSelect ® all Exon V5 50Mb kit and sequenced with a HiSeq2000 ® . The depth of coverage distribution of each PKP2 exon was analysed and compared to the mean coverage distribution of the cohort. Heterozygous PKP2 deletion was suspected in presence of coverage < –2 standard deviation (SD). All suspected large deletions were confirmed with qPCR. MLPA ® was performed in 50 supplementary unrelated ARVC probands and in our cohort to compare the accuracy of this method with exome sequencing. The analysis of coverage depth identified one patient with a heterozygous deletion of the whole PKP2 gene and in the family, a heterozygous deletion of PKP2 exon 4 which cosegregrated(Figure). qPCR and MLPA ® analysis confirmed this result. The prevalence of large deletions of PKP2 in gene negative familial ARVC was 10,5%. MLPA ® identified large PKP2 deletions in two additional unrelated probands. Our study shows that large PKP2 deletions are not infrequent in ARVC and should therefore be screened in patients with unidentified mutations. This study demonstrates that whole exome sequencing is an accurate technique to detect such mutations. However, MLPA ® appears as an efficient and costless technique in this purpose. Figure: Heterozygous PKP2 exon 4 deletion in the family