Therefore, DD presents with a triad of severe cardiomyopathy, skeletal myopathy, and mental retardation, of which cardiomyopathy dominates the clinical picture [3-4]. Here, we present the case of a patient with an atypical and milder version of Danon disease, i.e., cardiac manifestations in the absence of neurological and skeletal muscle pathology, caused by a previously unreported LAMP-2 gene mutation. The gene discussed is LAMP2; the disease is dentin dysplasia.