Your point in well noted but there some points I like to clarify, for the above example, I think you are mixing up rare genetic disease with that of diseases primarily found in certain population group. For example, hypertension and diabetes are diseases common among African americans. Nonetheless, you also find it in other ethnic group, what the data is showing in the case of African Americans, its better to treat them as a first line approach using Calcium Channel blockers in the case of hypertension rather than beta-blockers which would work in other ethnic group better. The idea is that drug company has an incentive in targeting research geared toward that population group because of the potential market available to them. Another example is that of Adult T-cell lymphoma/ leukemia which is common in Japan and Caribbean, while it is cause by HTLV-1, its distribution isn't significant among other population group. Researchers can now ask the question is there something is those population group that results in this. There is now an incentive for drug companies because you have Japanese population and 40 million population in the Caribbean. When it comes to rare genetic disorder one can say the potential money needed to invest to find solution isn't worth it but I remind you that medical research has a way of scientist trying to find one solution and finding another.

With regard to your statement "Don't forget that the current challenges in drug development are not the lack of knowledge about DNA profiles, but the understanding how to block/ trigger certain signalling cascades on the way to cancer or how to find new drug...", that statement isn't factual, there is actually a huge lack of genetic diversity as can be seen from the chart presented, most of the data presented primarily comes from someone of European ancestry. This is actually one of the issues currently be targeted to get more research targeted at specific ethnic group and more research to deal primarily with these groups. You can follow the Human Genome Project, lots of data, most of our indigenous tribes data aren't even catalog, we still have all of South American, Caribbean and Africa to cover.

This is probably dealing with another topic but I believe much of what we are trying to find out about our body and diseases are actually written in various group DNA. There are groups that have natural mutation that makes them immune to various viruses like HIV, HTLV as the resulting protein (receptor) is compatible. All these have clinical significance because once you find these among given DNA, there is a potential it can be reproduce in the lab and with the tools like CRISPR, there lots of potential we can solve many diseases are a genetic basis.

Thank you for commenting, appreciate it