Dopa-responsive dystonia (DRD) describes a group of neurometabolic disorders characterized by dystonia that typically shows diurnal fluctuations, that responds excellently to levodopa (L-dopa) and that is comprised of autosomal dominant dopa-responsive dystonia (DYT5a), autosomal recessive dopa-responsive dystonia (DYT5b) and dopa responsive dystonia due to sepiapterin reductase (SR) deficiency.