Autosomal dominant GTP cyclohydrolase I (AD GCH 1) deficiency (Segawa disease, dystonia 5; DYT 5)

Chang Gung Med J. Jan-Feb 2009;32(1):1-11.


Autosomal dominant GTP cyclohydrolase I (AD GCH 1) deficiency (Segawa disease) is an autosomal dominant dopa responsive dystonia caused by heterozygous mutation of the GCH 1 gene located on 14q22.1-q22.2. Although a number of mutations have been reported, the change remains highly stable within families, and causes a decrease in the tyrosine hydroxylase protein at the nigrostriatal (NS)-dopamine (DA) neuron terminal. In addition, decreased tetrahydrobiopterin levels early in the development affect DA receptors age-dependently, and produce a spectrum of specific symptoms attributed to neuronal changes traced to processes in the development of the NS-DA neuron, related striatal projection neurons, and the output projection of the basal ganglia.

Publication types

  • Review

MeSH terms

  • Dystonia / genetics*
  • Female
  • GTP Cyclohydrolase / deficiency*
  • Humans
  • Male


  • GTP Cyclohydrolase