Certain concepts of race are social constructs. E.G. A drug BiDil that was approved for African Americans but actually provided no race-based advantaged when people were segregated by genetic markers instead of self identified Race. In this context any efficacy with African Americans vs general Black Africans elsewhere in the world is absolutely attributable to social differences between groups (e.g. average exposure to environmental contaminants that increase the likelihood of heart disease and reduce the efficacy of normal treament)

You can find genetic markers that are associated with ethnic groups or diaspora of historical populations, the problem that a lot of scientist have is any implicit association that simply because you can find certain verifiable genetic differences between populations does not mean that all or any of those differences when studied (including drug efficacy) are necessarily associated with the true genetic markers for the closest thing that scientists have for race in biology.