CYP2D6 Genotype in Relation to Liver Toxicity Due to Tetrabenazine in Iraqi Patients with Hyperkinetic Movement Disorders

  • Zainab A. Abbood MOH
  • Shatha H. Ali
  • Nawfal M. Sheaheed
Keywords: Dystonia, chorea, Tetraberazine, Alpha and Beta dihydrotetrabenazine, CYP 450 2D6 enzyme polymorphism, liver function.



The  common types of movement disorders are ; dystonia which is a syndrome  of  repetitive muscle contractions. While , Huntington disease is autosomal dominant progressive neurodegenerative disorder, which is characterized by involuntary movements (“chorea”).

Tetrabenazine therapy has been shown to effectively control this movements compared with placebo.

Design the proper dosing approach for patients treated with tetrabenazine with genotype polymorphisms and their hepatic effect on patients.

A prospective case controlled study was carried on 50 patients whom    divided into 2 groups :first group involved 25 patients who had chorea, and group 2 included  patients with dystonia, whom treated with (tetrabenazine) for three months. In addition to control group involved 25 healthy subjects . Blood samples were collected at the beginning and after three months  to assess  liver function  in relation to genetic polymorphism of CYP 450 2D6 enzyme for both groups and measuring the plasma concentration of tetrabenazine , alpha and beta  dyhdrotetrabenazine.

The results show a significant CYP 450 2D6 enzyme polymorphism. And elevations of liver enzymes in the patient indicate hepatotoxicity of tetrabenazine and its metabolites,

Determination a genotype of the CYP 450 2D6  genes in Iraqi patients, in relation  to the safety and efficacy of tetrabenazine  .