Polymorphisms in the promoter region of DRD4 ( -120 bp duplication , -616C/G , and -521C/T ) were genotyped using allele-specific polymerase chain reaction analysis .
O O O O O O B-GeneOrGeneProduct O B-SequenceVariant I-SequenceVariant I-SequenceVariant O B-SequenceVariant O O B-SequenceVariant O O O O O O O O O O