18 Population differences

What about the differences between the populations?

Differences exist between world populations as to how frequent each of the 80 known variants of the CYP2D6 gene is. Although all modern humans have a common evolutionary origin in Africa over 100 000 years ago, migration across the globe has occurred since then. As migration occurred, breeding populations became relatively isolated from each other and over many thousands of years the relative frequency of the different variants present in each geographically distinct group around the world changed. This, together with the occurrence of random new mutations that generate new variants, means that different world populations carry different frequencies of CYP2D6 gene variants.

Individuals with three or more functional genes are called ultra-metabolisers. Numbers of these individuals vary from 40% (North Africa) and 26% (Oceania) to 12% (Middle East) and 8% (Americas). Individuals who are considered poor metabolisers are most common in populations of European decent, where as much as 8% of the population are of this status. One obvious implication is that a drug developed for one particular world market may prove potentially either useless or dangerous in other world populations.