[klevertree]

Author here. Enzyme polymorphisms are tricky and would require a whole different blog post. Some drugs they matter a lot for, some drugs they do not. I actually have not found any drugs with 10-fold variability that could be ascribed solely (or even mainly) to polymorphisms, although it doesn't seem impossible.

[opportune]

https://www.ncbi.nlm.nih.gov/books/NBK84174/

Here’s an article I found in 30s of searching (granted, I already knew Warfarin was hugely affected by CYP2D6) stating that equivalent maintenance doses of Warfarin can vary by a factor of >10 (from 0.5mg to 7mg) based on the CYP2D6 phenotype of the patient.

[atombender]

Don't know about 10x, but having the MTHFR mutation genotype 667TT reduces folate activation [1] by 70-80%, which is a problem with drugs that require folate supplementation, like methotrexate.

[1] https://www.snpedia.com/index.php/Rs1801133