The multiple faces of Danon disease

Dilated Cardiomyopathy and Systolic Heart Failure in a Female Patient With Danon Disease

Danon disease commonly manifests as isolated hypertrophic cardiomyopathy in female patients. The diagnosis is easily missed as it is rare and its pathophysiology is poorly understood. Without early diagnosis and treatment with heart transplantation, cardiomyopathy may progress to heart failure. We present the case of an adolescent female with Danon disease who presented with heart failure with reduced ejection fraction secondary to dilated cardiomyopathy. Her original presentation included a six-month history of shortness of breath, vomiting, and abdominal pain. Further workup revealed pelvic ascites and dilated cardiomyopathy with signs of heart failure. Genetic testing confirmed the diagnosis, revealing a previously undocumented amino acid substitution in the lysosomal-associated membrane protein-2 (LAMP2) gene. The patient received a heart transplant which led to an improvement in her symptoms. The patient's unique symptomatology illustrates the importance of early cardiac monitoring and transplantation if Danon disease is suspected. This uncommon presentation of dilated cardiomyopathy followed by psychiatric impairment, developmental disability, and unique LAMP2 genetic substitution provides a rare phenotype of Danon disease.

A critical approach for successful use of circulating microRNAs as biomarkers in cardiovascular diseases: the case of hypertrophic cardiomyopathy

MicroRNAs (miRNAs) are small noncoding RNA molecules that act as major regulators of gene expression at the post-transcriptional level. As the potential applications of miRNAs in the diagnosis and treatment of human diseases have become more evident, many studies of hypertrophic cardiomyopathy (HCM) have focused on the systemic identification and quantification of miRNAs in biofluids and myocardial tissues. HCM is a hereditary cardiomyopathy caused by mutations in genes encoding proteins of the sarcomere. Despite overall improvements in survival, progression to heart failure, stroke, and sudden cardiac death remain prominent features of living with HCM. Several miRNAs have been shown to be promising biomarkers of HCM; however, there are many challenges to ensuring the validity, consistency, and reproducibility of these biomarkers for clinical use. In particular, miRNA testing may be limited by pre-analytical and analytical caveats, making our interpretation of results challenging. Such factors that may affect miRNA testing include sample type selection, hemolysis, platelet activation, and renal dysfunction. Therefore, researchers should be careful when developing appropriate standards for the design of miRNA profiling studies in order to ensure that all results provided are both accurate and reliable. In this review, we discuss the application of miRNAs as biomarkers for HCM.