Its aetiology remains uncertain with various suggested pathogenesis such as peripheral and central neuropathy disorders, psychological disorders, changes in gonadal, adrenal and neurosteroid levels, a dopamine D2 receptor (DRD2) 957C>T genotype and the association between BMS and other neurological diseases such as Parkinson’s disease (40, , –43). The gene discussed is DRD2; the disease is nervous system disorder.