MICU1 and myopathy: Abnormal mitochondrial Ca2+ handling due to biallelic MICU1 variants causes a very rare neuronal and muscular disorder in humans termed the myopathy with extrapyramidal signs (MPXPS; OMIM #615673), characterized by impaired cognition, early muscle weakness, elevated serum creatine kinase (CK), and an extrapyramidal movement disorder [1, 2].