Finally, it is also possible that the extensive loss of SP+ neurons by grade 3 HD plays a role in the observed dystonia, since mutant mice with prenatal or postnatal ablation of D1 dopamine receptor-possessing neurons (mainly SP+ neurons) typically have dystonia as a symptom.68,69 These results must be viewed with caution, however, since ablation of neurons possessing D1 receptors also eliminates D1 receptor-bearing cortical neurons. Here, DRD1 is linked to Dystonia.