Such underlying prevalence might be consistent with the incidence of observed neurologic adverse events with mefloquine prophylaxis, particularly when coupled with an as-yet-unclear population prevalence of either MDR1 polymorphisms, co-administration of medication which may further inhibit P-gp function, or other conditions such as liver dysfunction which may decrease metabolism and, therefore, lead to increases in neuronal mefloquine concentrations. The gene discussed is ABCB1; the disease is Decreased liver function.