In our patient, HCM and arrhythmogenic right ventricular dysplasia were ruled out after careful checking of cardiac histology, and we found no other variant among the unexplained sudden death genes, like KCNH2. As the literature shows no report of a rhythm disorder in isolated p.Glu134Ala, we believe that the heterozygous variation in the MYL2 gene did not play a significant role in the sudden death of this child. This evidence concerns the gene MYL2 and Arrhythmogenic right ventricular dysplasia.