<s>[INST] <<SYS>> This is a medical question of type : frequency <</SYS>> How many people are affected by biotin-thiamine-responsive basal ganglia disease ? [/INST] Biotin-thiamine-responsive basal ganglia disease is a rare disorder; its prevalence is unknown. Approximately 48 cases have been reported in the medical literature; most of these are individuals from Arab populations. </s>