Introduction:

Danon syndrome was first described by Danon MJ in 1981. This rare disease is a triad consisting of dilated cardiomyopathy, myopathy and mental retardation. The etiology of the disease is associated with mutations in the LAMP2 gene on chromosome X. To date, only mutations in the LAMP2 gene have been associated with the disease.

Case presentation:

We present the case of a male patient who was initially suspected of being affected by Pompe disease and polymyositis without response to the treatments. He required implantation of pacemakers, and posteriorly a cardioverter defibrillator and isolation of pulmonary veins. Therefore, due to the lack of clarity in the diagnosis, endomyocardial biopsy and genetic studies were performed in order to establish the diagnosis. We found a novel mutation in the LAMP2 gene which had not been reported previously.

Discussion:

Danon disease is a dominant hereditary syndrome linked to the X chromosome. Danon, specifically is caused by an accumulation of glycogen in muscle cells without alterations in the enzymes responsible for its metabolism. It compromises cardiovascular, muscular and neurological systems, liver and spleen. Cardiac tissue exhibits severe fibrosis, which favors the development of supraventricular and ventricular arrhythmias. As for the diagnosis, the gold standard test is genetic analysis. The treatment is focused on the management of the manifestations that the patient presents, since there is no specific treatment.

Conclusions:

Danon disease requires further studies in order to obtain epidemiological data for this condition. To date, only mutations in the LAMP2 gene have been documented as the main etiology of Danon disease. We found a single nucleotide deletion in LAMP2 resulting in a frameshift mutation which is the probable cause of Danon disease in this patient.