Blacks have more stress in their lives because of being marginalized members of society and the implications of this. Not necessarily in that order. The same genes that protect from malaria are at cause for sickle cell anemia. Some of the diseases you mention are clearly keyed to lifestyle, such as some cancers, AIDS and adult diabetes. The incidences of such diseases change when individuals or groups change the lifestyle patterns that make them susceptible.
Race is irrelevent unless the lifestyle choices are more a part of one culture or another.
Finally, decisions to seek treatment early and being able to get quality treatment early are key in some of the diseases you mention, such as cancer and heart disease. This would be tied to a group's economic position, which clearly has a race factor - in America at least. In the final years of his life, my grandfather had Alzheimer's disease. But he did not die of it. Even as a young child, it hurt me so much to see him in such a state because I loved him, and still love him, so much.