A phenocopy of sarcomeric hypertrophic cardiomyopathy: LAMP2 cardiomyopathy (Danon disease) from China

This editorial refers to ‘Danon disease as a cause of concentric left ventricular hypertrophy in patients who underwent endomyocardial biopsy’†, by Z. Cheng et al., on page 649 Hypertrophic cardiomyopathy (HCM) is the most common genetic heart disease characterized by otherwise unexplained left ventricular (LV) hypertrophy, and caused by a multitude of mutations in genes encoding proteins of the cardiac sarcomere.1–3 Notably, HCM is heterogeneous in terms of phenotypic expression, clinical presentation and course, as well as management strategies, i.e. with severe disease consequences in some patients but a benign course and normal life expectancy in many others.2,3 Recently, there has been increasing recognition that other uncommon inherited diseases may mimic the phenotypic and clinical features of sarcomeric HCM, but are caused by distinctly different gene mutations.4–7 These conditions include most prominently Fabry disease (X-linked α-galactosidase deficiency with glycosphingolipid deposition), PRKAG2 (regulatory subunit of adenosine monophosphate-activated protein kinase), and LAMP2 (a lysosomal storage disease, also known as Danon disease) (Figure 1).4–7