Severe cardiomyopathy associated with the VCP p.R155C and c.177_187del MYBPC3 gene variants.

Inclusion Body Myopathy, Paget's Disease of Bone, with Frontotemporal Dementia is a progressive autosomal dominant disease that affects the ubiquitin-proteasome complex, that is caused by variants in the Valosin Containing Protein (VCP) gene. We report the first case of concurrent pathogenic variants in both MYBPC3 and VCP that led to earlier onset of congestive heart failure with features of dilated cardiomyopathy. Cardiomyopathy has previously been associated with VCP inclusion body myopathy mostly at an advanced stage of the disease. Due to acute onset of cardiomyopathy in a previous asymptomatic individual, a cardiomyopathy gene panel was obtained which revealed an additional c.177_187del variant of the MYBPC3 gene. We report a first case of concurrent pathogenic variants in both c.177_187del gene of MYBPC3 and p.R155C VCP that led to earlier onset and a more severe form of the cardiomyopathy.