Cardiac Transplantation in Danon Disease.

BACKGROUND: Danon disease (DD) is a rare X-linked dominant cardioskeletal myopathy caused by mutations in the lysosome-associated membrane protein-2 (LAMP-2) gene that is usually lethal without cardiac transplantation. The purpose of this study was to characterize post-transplant outcomes in a large cohort of patients with DD who underwent cardiac transplantation. METHODS: The clinical phenotype and outcome data of patients with DD who underwent cardiac transplantation (n = 38; 19 males and 19 females) were obtained from 8 centers. Study outcomes included graft survival, defined as death or retransplantation, and episodes of acute cellular and antibody-mediated rejection and cardiac allograft vasculopathy at 1 year. RESULTS: Median follow-up time after transplantation for the entire cohort was 4.4 years (IQR: 1.5-12.8 years). The median age at transplant for the cohort was 20.2 years (15.8-27.9 years), with no difference in age between sexes. Median pretransplant left-ventricular ejection fraction for the entire cohort was 30% (range 11%-84%). Males had higher pretransplant aspartate aminotransferase, alanine aminotransferase and creatine phosphokinase levels than females (P < 0.001). There were 2 deaths in the entire cohort and 2 retransplants. There was no difference in actuarial graft survival between males and females (P = 0.8965); the estimated graft survival was 87.1% (95%CI: 63.6%-95.9%) at 5 years. One episode (2.7%) of antibody-mediated rejection, grade 2, and 7 episodes (19%) of acute cellular rejection, grade 2 or 3, were reported in patients who survived to discharge (6 females and 1 male; P = 0.172). CONCLUSIONS: Heart transplantation outcomes are acceptable in DD with high probabilities of 5-year graft survival for males and females suggesting that cardiac transplantation is an effective treatment option for DD patients.

Heart transplantation in Danon disease: Long term single centre experience and review of the literature.

Danon disease is characterized by hypertrophic cardiomyopathy, skeletal myopathy, and intellectual disability due to deficiency of the lysosome-associated membrane protein-2 (LAMP-2). Although heart transplantation is considered an option for end stage Danon cardiomyopathy, scarce information is available about long term follow up. We report on long term follow up (14.7 years, IQ range 9-21 years) of 4 patients, transplanted for Danon disease cardiomyopathy, showing two LAMP-2 gene variants, the novel c.815T > C and the previously reported c.294G > A. We have also analysed previous published paper on this topic comparing available data from different follow up. Being a skeletal and cardiac muscle disease, with systemic effects, long term results about HTx are indispensable to justify any treatments in this subset of patients.

Heart transplantation in two adolescents with Danon disease.

Danon disease (DD) is an X-linked dominant disorder caused by a mutation in the lysosomal-associated membrane protein-2 (LAMP-2) gene coding for the LAMP-2 protein. We report two cases of successful heart transplantation (HT) in adolescent brothers with DD, including one who was bridged to HT for 34 days with a HeartWare left ventricular assist device. In both patients, the post-transplant course was complicated by profound skeletal muscle weakness that resolved with corticosteroid withdrawal. These cases highlight that both HT and ventricular assist device support are feasible in patients with DD. Corticosteroid use may exacerbate skeletal myopathy, and therefore, steroid minimization may be warranted whenever possible.

Repeat Cardiac Transplant Indicated by Severe Cardiac Allograft Vasculopathy in a Patient With Danon Disease.

Danon disease is a rare, X-linked dominant, lysosomal storage disorder, presenting with cardiomyopathy mostly in adolescent men. Male patients face a high mortality rate and rarely live to the age of 25 years unless they receive a heart transplant. Because they generally undergo heart transplantation at a young age, many patients ultimately face both short- and long-term complications. We present a 32-year-old man diagnosed with Danon disease; a nonsense mutation in the LAMP-2 gene. Progressive heart failure symptoms resulted in initial heart transplant at age 27 years. He subsequently developed severe cardiac allograft vasculopathy that led to graft failure requiring a redo orthotopic heart transplant. This is one of only two reported Danon disease cases described to date surviving repeat orthotopic heart transplants. We present this case to highlight the importance of heart transplantation in the management of Danon disease, to emphasize the risk of cardiac allograft vasculopathy post-transplant, and to discuss management strategies.

Malignant cardiac phenotypic expression of Danon disease (LAMP2 cardiomyopathy).

INTRODUCTION: Danon disease is an X-linked lysosomal condition that causes a deficiency of lysosome-associated membrane protein 2 (LAMP2) gene. It is characterized clinically by a triad of skeletal myopathy, cardiomyopathy, and intellectual disability. METHODS: We examined clinical, echocardiographic, and genetic data on 5 patients with Danon disease, highlighting their clinical course and outcomes. RESULTS: All patients presented phenotypically with hypertrophic cardiomyopathy and later developed systolic dysfunction. The mean age at diagnosis was 19years (11-31years). All patients had diastolic dysfunction (mean e' of 5cm/s [3.5-6cm/s], mean E/e' of 17 [15-21]). Three patients required cardiac transplantation (ages 15, 27, and 42). Of the two deaths in this group, both were in women. CONCLUSION: We highlight the aggressive cardiac phenotype of Danon disease in our clinical experience with rapid progression to end-stage cardiomyopathy; this progression occurred in both men and women. A timely diagnosis and an early referral for cardiac transplantation is crucial for improved outcomes.

Late profound muscle weakness following heart transplantation due to Danon disease.

INTRODUCTION: Postoperative muscle weakness is a serious complication in surgical intensive care patients. It is mostly described as critical illness polyneuromyopathy. Risk factors include intensive care length of stay, sepsis, poor glycemic control, and combined use of corticosteroids and neuromuscular blocking agents, malnutrition, and electrolyte imbalance. METHODS: We report a case of late-progressive, profound weakness after heart transplantation for noncompaction cardiomyopathy which required prolonged mechanical ventilation. The patient's muscle strength recovered completely after prolonged rehabilitation. RESULTS: Electromyographic assessment showed myopathy. Muscle biopsy revealed Danon disease, a genetic disorder affecting the lysosomal-associated membrane protein 2 gene (LAMP2). CONCLUSIONS: The finding of this genetic disorder was unexpected, because the preoperative echocardiographic diagnosis of noncompaction cardiomyopathy has not been reported in Danon disease. This report underlines the need for early availability of pathology results from the explanted heart, which showed the same disorder.

Danon disease: focusing on heart.

Danon disease is a rare X-linked dominant lysosomal disease due to the primary deficiency of lysosome-associated membrane protein 2 (LAMP2) gene. Cardiomyopathy, skeletal myopathy and mental retardation are the typical triad of Danon disease. More than 60 LAMP2 mutations have been reported. The molecular mechanism is defects in LAMP2 protein (due to LAMP2 mutation) which causes insidious glycogen accumulation in cardiac muscle cells and resulting in cardiac hypertrophy and electrophysiological abnormalities. However, there are significant differences between the male and female Danon disease patients with regard to clinical features and cardiac manifestations. The clinical symptoms are variable, from asymptomatic to sudden cardiac death. Wolff-Parkinson-White syndrome is more common in male than female patients. Hypertrophic cardiomyopathy is predominant in male patients, whereas the similar prevalence of hypertrophic and dilated cardiomyopathy in female patients. Male patients are diagnosed usually at teenage, whereas the diagnosis and events occurred approximately 15 years later in female than male patients. Heart transplantation is the reliable treatment once the occurrence of heart failure and should be considered as early as possible due to its rapid progression.

Danon disease: case report and detection of new mutation.

Danon disease is an X-linked disorder resulting from mutations in the lysosome-associated membrane protein-2 (LAMP2) gene. We report a male patient with skeletal myopathy, mental retardation, and massive hypertrophic obstructive cardiomyopathy necessitating heart transplantation. Immunohistochemistry of skeletal muscle and leukocytes, western blot analysis of leukocytes and cardiac muscle, flow cytometry, and DNA sequencing were performed. Muscle biopsy revealed autophagic vacuolar myopathy and lack of immunohistochemically detectable LAMP-2. Diagnosis of Danon disease was confirmed by western blot analysis of myocardial tissue and peripheral blood sample of the patient showing deficiency of LAMP-2 in myocardium and leukocytes. Moreover, absence of LAMP-2 in lymphocytes, monocytes and granulocytes was shown by flow cytometric analysis. Genetic analysis of the LAMP2 gene revealed a novel 1-bp deletion at position 179 (c.179delC) at the 3' end of exon 2, resulting in a frameshift with a premature stop codon.

Clinical outcome and phenotypic expression in LAMP2 cardiomyopathy.

CONTEXT: Mutations in X-linked lysosome-associated membrane protein gene (LAMP2; Danon disease) produce a cardiomyopathy in young patients that clinically mimics severe hypertrophic cardiomyopathy (HCM) due to sarcomere protein mutations. However, the natural history and phenotypic expression of this newly recognized disease is incompletely resolved and its identification may have important clinical implications. OBJECTIVES: To determine the clinical consequences, outcome, and phenotypic expression of LAMP2 cardiomyopathy associated with diagnostic and management strategies. DESIGN, SETTING, AND PATIENTS: Clinical course and outcome were assessed prospectively in 7 young patients (6 boys) with defined LAMP2 mutations from the time of diagnosis (age 7-17 years; median, 14 years) to October 2008. Phenotypic expression of this disease was assessed both clinically and at autopsy. MAIN OUTCOME MEASURES: Progressive heart failure, cardiac death, and transplant. RESULTS: Over a mean (SD) follow-up of 8.6 (2.6) years, and by age 14 to 24 years, the study patients developed left ventricular systolic dysfunction (mean [SD] ejection fraction, 25% [7%]) and cavity enlargement, as well as particularly adverse clinical consequences, including progressive refractory heart failure and death (n = 4), sudden death (n = 1), aborted cardiac arrest (n = 1), or heart transplantation (n = 1). Left ventricular hypertrophy was particularly marked (maximum thickness, 29-65 mm; mean [SD], 44 [15] mm), including 2 patients with massive ventricular septal thickness of 60 mm and 65 mm at ages 23 and 14 years, respectively. In 6 patients, a ventricular pre-excitation pattern at study entry was associated with markedly increased voltages of R-wave or S-wave (15-145 mm; mean [SD], 69 [39] mm), and deeply inverted T-waves. Autopsy findings included a combination of histopathologic features that were consistent with a lysosomal storage disease (ie, clusters of vacuolated myocytes) but also typical of HCM due to sarcomere protein mutations (ie, myocyte disarray, small vessel disease, myocardial scarring). CONCLUSIONS: LAMP2 cardiomyopathy is a profound disease process characterized by progressive clinical deterioration leading rapidly to cardiac death in young patients (<25 years). These observations underscore the importance of timely molecular diagnosis for predicting prognosis and early consideration of heart transplantation.

Novel Lamp-2 gene mutation and successful treatment with heart transplantation in a large family with Danon disease.

Lysosome-associated membrane protein-2 deficiency (LAMP-2 deficiency), or Danon disease, is a rare X-linked lysosomal disease characterized by cardiomyopathy, vacuolar myopathy, and mental retardation. Less than 20 families with mutations of the Lamp-2 gene have been reported. We describe a family from Sardinia with eight affected patients (4 females and 4 males) and a novel mutation in exon 2 of the Lamp-2 gene (c.102_103delAG). Females developed isolated cardiomyopathy in adulthood, whereas males presented with cardiomyopathy, myopathy, and mental retardation before the age of 20 years. Cardiomyopathy was lethal in three females in their 40s and in three males before the age 20 years. One patient was successfully treated by heart transplantation with more than 5-year follow-up. This study demonstrates that Danon disease is a frequently fatal condition that is potentially treatable with heart transplantation.