For example, the DAT1/SLC6A3 VNTR polymorphism modulates drug-induced cue reactivity in the striatum in AD patients,15 striatal DAT availability and the severity of alcohol withdrawal.16 As the DAT1 9 R allele has been associated with reduced DAT expression,17 it may be that the allele leads to accumulation of synaptic DA, which results in increased reward processing. The gene discussed is SLC6A3; the disease is Alzheimer disease.