RESUMO
Genes for dopamine receptor DRD4 and dopamine transporter DAT1 are highly polymorphic. Two alleles of these genes, namely the DRD4.7 and the DAT1*9 are frequently associated to the attention deficit disorder with hyperactivity. In Europe, the allele for DRD4 receptor with four repetitions (DRD4.4) has the highest frequency, with a median of 69 percent, followed by DRD4.7, with a frequency of 15 percent. South American indigenous populations have higher frequencies for DRD4.7 (61 percent) than for DRD4.4 (29 percent). The ten repetition allele for DAT1 transporter has a high frequency among Europeans (72 percent) and Amerindians (100 percent). The allele DAT1*9 is the second most frequent allele. Aim: To study the frequency of DRD4 and DAT1 alleles in a Chilean population sample. Material and methods: One hundred serum samples were obtained from blood donors in two public hospitals in Santiago. Polymorphic regions for DRD4 and DAT1 were amplified by polymerase chain reaction. Results: The allele DRD4.4 had a frequency of 59 percent and DRD4.7 a frequency of 27 percent. The allele DAT1*10 had a frequency of 74 percent, followed by DAT 1*9, with a frequency of 23 percent. Discussion: In a Chilean population sample, the frequency of DRD4 and DAT1 alleles was very similar to that of European populations