There is more genetic variation within a what we might call a race than between them. And it's interesting to note that the genetic diversity of Eurasian populations is in large part contained within the much greater diversity of Africa. In some sense we're all Africans. On top of that there has been a good amount of mixing, both historically and in the present day.
To think in terms of "races" might lead one to hold a mental model of impermeable boundaries between populations that in many cases were never present, and certainly aren't today. Geneticists tend to use the word "population" instead, since it doesn't connote any unhelpful assumptions about uniform or fixed phenotypes within a well-defined species subgroup.
Of course there are certain obvious environmental adaptations that have been selected for in different geographies/climates, as well random genetic drift between distant populations. Sometimes those difference might have medical relevance, and you can make statistical generalisations about the prevalence and distribution of genetic markers within any group you like. But for most medical and public policy applications it is likely most useful to focus on populations within an administrative area, and increasingly, individualised medicine.
This being your first sentence doesn't warrant continued reading.