Congenital myopathies are clinically and genetically heterogeneous, and are classified based on typical structural abnormalities on muscle sections. Recessive mutations in the striated muscle preferentially expressed protein kinase (SPEG) were recently reported in patients with centronuclear myopathy (CNM) associated in most cases with dilated cardiomyopathy. Here we report the identification of novel biallelic truncating SPEG mutations in a patient with moderate congenital myopathy without clinical and histological hallmarks of CNM and without cardiomyopathy. This study expands the phenotypic spectrum of SPEG-related myopathy and prompts to consider SPEG for congenital myopathies without specific histological features.
Keywords: Centronuclear myopathy; MTM1; SPEG; congenital myopathy; myotubular myopathy; myotubularin.