Anti-LAMP2 monoclonal antibody, clone HM3B8

Hypertrophic cardiomyopathy (HCM) and restrictive cardiomyopathy (RCM) present a high risk for sudden cardiac death in pediatric patients. The aim of this study was to identify disease-associated genetic variants in Japanese patients with pediatric HCM and RCM. We analyzed 67 cardiomyopathy-associated genes in 46 HCM and 7 RCM patients diagnosed before 16 years of age using a next-generation sequencing system. We found that 78% of HCM and 71% of RCM patients carried disease-associated genetic variants. Disease-associated genetic variants were identified in 80% of HCM patients with a family history and in 77% of HCM patients with no apparent family history (NFH). MYH7 and/or MYBPC3 variants comprised 76% of HCM-associated variants, whereas troponin complex-encoding genes comprised 75% of the RCM-associated variants. In addition, 91% of HCM patients with implantable cardioverter-defibrillators and infant cases had NFH, and the 88% of HCM patients carrying disease-associated genetic variants were males who carried MYH7 or MYBPC3 variants. Moreover, two disease-associated LAMP2, one DES and one FHOD3 variants, were identified in HCM patients. In this study, pediatric HCM and RCM patients were found to carry disease-associated genetic variants at a high rate. Most of the variants were in MYH7 or MYPBC3 for HCM and TNNT2 or TNNI3 for RCM.

Danon disease is an X-linked systemic disorder characterized by left ventricular hypertrophy, mental retardation, and skeletal myopathy affecting young men. Electrocardiogram usually displays a Wolff Parkinson White preexcitation pattern. Less has been reported about the phenotype in women, although later-onset cardiac symptoms have been described. The aim of this study was to expand the knowledge of the phenotype of Danon disease in women. We clinically followed and evaluated with echocardiography, cardiac magnetic resonance imaging (cMRI), and genetic testing a family affected by Danon disease in which 2 men and 6 women showed a severe arrhythmogenic phenotype. Affected family members carried a nucleotide substitution at position 294 in exon 3 (c.294 G -> A) that changed a tryptophan residue to a stop codon at position W98X in the lysosome-associated membrane protein 2 (LAMP2) gene. Four women died suddenly (1 aborted) at 37 to 54 years of age. Wolff Parkinson White pattern with atrioventricular block was detected in 2 of 6 women. Four had successful pregnancies without symptoms of heart failure. cMRI showed late gadolinium enhancement areas in a clinically healthy woman who was a mutation carrier. Two patients underwent heart transplantation; histology of explanted hearts demonstrated severe interstitial fibrosis, hypertrophic cardiomyocytes with cytoplasmic vacuoles, and myofibrillar disarray. In conclusion, LAMP2 mutation can cause a severe arrhythmogenic phenotype in women that includes a high risk of sudden death. cMRI may be useful in women harboring LAMP2 mutations to permit early detection of cardiac involvement and guide timely considerations of implantable cardioverter defibrillator therapy. Heart transplantation should be considered at onset of heart failure symptoms owing to rapid progression of the disease. (C) 2012 Elsevier Inc. All rights reserved. (Am J Cardiol 2012;109:406-411)