A rare, life-threatening neurometabolic disease characterized by a progressive neurodegenerative course, epilepsy, retinopathy and progressive cardiomyopathy. The disease is HSD10 mitochondrial disease (Monarch Disease Ontology entry MONDO_0010327). Also known as: 17-beta-hydroxysteroid dehydrogenase 10 deficiency, 17-beta-hydroxysteroid dehydrogenase X deficiency, 2-methyl-3-hydroxybutyric aciduria, 2-methyl-3-hydroxybutyryl-CoA dehydrogenase deficiency, 3-hydroxyacyl-CoA dehydrogenase 2 deficiency, HSD10 deficiency, HSD10 mitochondrial disease, X-linked dominant, HSD10MD.