Novel ATP2A2 Gene Mutation c.118G>A Causing Keratinocyte and Cardiomyocyte Disconnection in Darier Disease.

Darier disease (DD) is an autosomal dominant disorder due to pathogenic variants of the ATP2A2 gene that causes an isolated skin manifestation based on keratinocyte disconnection and apoptosis. Systemic manifestations of DD have not been demonstrated so far, although a high incidence of neuropsychiatric syndromes suggests an involvement of the central nervous system. We report that the pathogenic ATP2A2 gene variant c.118G>A may cause cardiac involvement in patients with DD, consisting of keratinocyte and cardiomyocyte disconnection. Their common pathologic pathway, still unreported, was documented by both skin and left ventricular endomyocardial biopsies because cardiac dilatation and dysfunction appeared several decades after skin manifestations. Keratinocyte disconnection was paralleled by cardiomyocyte separation at the lateral junction. Cardiomyocyte separation was associated with cell disarray, sarcoplasmic reticulum dilatation, and increased myocyte apoptosis. Clinically, hyperkeratotic skin papules are associated with chest pain, severe muscle exhaustion, and ventricular arrhythmias that improved following administration of aminophylline, a phosphodiesterase inhibitor enhancing SERCA2 protein phosphorylation. Cardiac pathologic changes are similar to those documented in the skin, including cardiomyocyte disconnection that promotes precordial pain and cardiac arrhythmias. Phosphodiesterase inhibitors that enhance SERCA2 protein phosphorylation may substantially attenuate the symptoms.

Novel dilated cardiomyopathy associated to Calreticulin and Myo7A gene mutation in Usher syndrome.

We report a novel cardiomyopathy associated to Usher syndrome and related to combined mutation of MYO7A and Calreticulin genes. A 37-year-old man with deafness and vision impairment because of retinitis pigmentosa since childhood and a MYO7A gene mutation suggesting Usher syndrome, developed a dilated cardiomyopathy with ventricular tachyarrhythmias and recurrent syncope. At magnetic resonance cardiomyopathy was characterized by left ventricular dilatation with hypo-contractility and mitral prolapse with valve regurgitation. At left ventricular endomyocardial biopsy, it was documented cardiomyocyte disconnection because of cytoskeletal disorganization of cell-to-cell contacts, including intercalated discs, and mitochondrial damage and dysfunction with significant reduction of adenosine triphosphate production in patient cultured fibroblasts. At an extensive analysis by next-generation-sequencing of 4183 genes potentially related to the cardiomyopathy a pathogenic mutation of calreticulin was found. The cardiomyopathy appeared to be functionally and electrically stabilized by a combination therapy including carvedilol and amiodarone at a follow-up of 18 months.