dimethylglycine dehydrogenase deficiency (Monarch Disease Ontology id MONDO_0011610) is an extremely rare autosomal recessive glycine metabolism disorder characterized clinically in the single reported case to date by muscle fatigue and a fish-like odor. This is an n-of-1 use case where only one patient or family has been described with this disorder. Also known as: DMG dehydrogenase deficiency, DMGDH deficiency, dimethylglycine dehydrogenase activity disease, disorder of dimethylglycine dehydrogenase activity.