Multimodality Imaging of Danon Disease in a Patient with a Novel LAMP2 Mutation

Abstract

Danon disease is a rare X-linked genetic disorder presenting typically as a triad of mental retardation, skeletal myopathy, and hypertrophic cardiomyopathy (HCM). Mutations of the lysosome-associated membrane protein 2 (LAMP2) gene lead to impaired lysosomal functioning and the accumulation of intracellular glycogen. Similarly to Pompe disease (glycogen storage disease type II), with which it was initially confused, Danon disease is seen as a glycogen storage disorder, but is not related to α-glucosidase enzyme deficiency. Instead, Danon disease results from an LAMP2-associated impairment of lysosomal membrane integrity. Cardiac involvement is a prominent clinical feature of Danon disease, in which young, often adolescent patients present with apparent left ventricular hypertrophy (LVH) and arrhythmias. Danon disease is commonly mistaken for sarcomeric HCM, despite being a lysosomal storage disease. The distinction between these two disorders is important because Danon disease has a more rapid disease progression and higher mortality. Here we describe the importance of multimodality imaging of Danon disease in a patient with a novel LAMP2 mutation.