Janssens seems less skeptical of 23andMe's paper on polygenic score for type 2 diabetes [1][2], which -- interestingly -- positively cites the Khera 2018 paper on polygenic score for heart disease that she critiqued. Some researchers are skeptical, but the medical community generally seems to consider polygenic scores promising for tests [3][4].
> you haven't posited how Bob's mapped genome sitting in 23andme will be used for medical treatment.
Early intervention. Polygenic scores could be used for medical treatment by motivating earlier intervention. That could include stronger recommendations for better diet and exercise, closer monitoring programs, or more precise prescriptions. That, in turn, could reduce disease burden.
[1] https://twitter.com/cecilejanssens/status/113707970323438797...
[2] https://permalinks.23andme.com/pdf/23_19-Type2Diabetes_March...
[3] https://twitter.com/EricTopol/status/1129780543434964993
[4] https://journals.plos.org/plosmedicine/article?id=10.1371/jo...