Researchers have begun to study the pharmacologic properties of medications in different ethnic minority groups and national populations. In this context, delimitation of the ethnic or national category is essential to ensure sufficient cultural and genetic homogeneity to render the study meaningful. In Spain, the ''Latino'' population tends to have its origins in the Andean region of South America. There is some evidence that there is genetic variation in isoenzymes CYP2D6 and CYP1A2 1 in Amerindians, which impacts the gene that encodes the serotonin transporter, 1,2 which would appear to impact the metabolism of SSRI drugs but much less so dual-acting drugs such as duloxetine.