ABSTRACT
Dopa-responsive dystonia (DRD) is a clinical term first proposed by Nygaard et al. (1) and later modified by Calne (2). Initially, this term was used to describe an autosomal-dominant DRD, now termed autosomal-dominant guanosine triphosphate cyclohydrolase I (AD GCH-I) deficiency. However, it is now used more comprehensively, and refers to all dystonias responding to levodopa. This chapter will review the clinical characteristics of the DRD, but will emphasize AD GCH-I deficiency and autosomal-recessive tyrosine hydroxylase (TH) deficiency.
