Clinical features of pediatric Danon disease and the importance of early diagnosis

Successful therapy in a cohort with early onset Danon disease (DD) highlights the potential importance of earlier disease recognition. We present experience from the largest National Pediatric Center in Russia for cardiomyopathy patients. This report focuses on identification of early clinical features of DD in the pediatric population by detailed pedigree analysis and review of medical records. RESULTS: Nine patients (3 females) were identified with DD at the Russian National Medical Research Center of Children's Health ("National Pediatric Center") aged birth to 16 years. At presentation/evaluation: all patients had left ventricular hypertrophy (LVH), ECG features of Wolff-Parkinson-White (WPW), and an increase in hepatic enzymes (particularly lactate dehydrogenase (LDH)); three had marked increase in NT-proBNP; two had HCM with impaired LV function; one had LVH with LV noncompaction; five had arrhythmia with paroxysmal supraventricular and/or ventricular tachycardia. Two teenagers died at ages 16-17 from refractory heart failure and two underwent heart transplantation. All patients were found to have a pathogenic/likely pathogenic variant in the LAMP2 gene, six patients had no family history and a de novo evolvement was documented in 4/6 of those available for genetic tested. Retrospective review related to family background and earlier clinical evaluations revealed a definitive or highly suspicious family history of DD in 3, early clinical presentation with cardiac abnormalities (ECG, echo) in 3, and cerebral, hepatic and/or neuromuscular symptoms in 5. Abnormalities were detected 9,5 months to 5,8 years, median 3,5 years prior to referral to the National Pediatric Center. CONCLUSION: The earliest clinical manifestations of Danon disease occur in the first 12 years of life with symptoms of skeletal muscle and cerebral disease, raised hepatic enzymes, and evidence of cardiac disease on ECG/echo.

The Double Mutation DSG2-p.S363X and TBX20-p.D278X Is Associated with Left Ventricular Non-Compaction Cardiomyopathy: Case Report

Left ventricular non-compaction cardiomyopathy (LVNC) is a rare heart disease, with or without left ventricular dysfunction, which is characterized by a two-layer structure of the myocardium and an increased number of trabeculae. The study of familial forms of LVNC is helpful for risk prediction and genetic counseling of relatives. Here, we present a family consisting of three members with LVNC. Using a next-generation sequencing approach a combination of two (likely) pathogenic nonsense mutations DSG2-p.S363X and TBX20-p.D278X was identified in all three patients. TBX20 encodes the cardiac T-box transcription factor 20. DSG2 encodes desmoglein–2, which is part of the cardiac desmosomes and belongs to the cadherin family. Since the identified nonsense variant (DSG2-p.S363X) is localized in the extracellular domain of DSG2, we performed in vitro cell transfection experiments. These experiments revealed the absence of truncated DSG2 at the plasma membrane, supporting the pathogenic relevance of DSG2-p.S363X. In conclusion, we suggest that in the future, these findings might be helpful for genetic screening and counseling of patients with LVNC.