I see what you are saying but;
I don't know any clinical chemists and I have exhaustively searched the net but all the sites of interest are in other countries. I was just hoping someone on here might know where to point me to.
Or were you talking about the relevance between CYP2D6 and metabolism of codeine etc? From what I understand; CYP2D6 strips the methyl group off about 10% of the methylmorphine (codeine) turning it into morphine. Obviously people defficient in this enzyme will get little or no analgesic effect. Apparently it is required to properly metabolise a large number of drugs.
More information can be found here:
CYP2D6 - Wikipedia, the free encyclopedia (yes i know its a wiki article but appears to be accurate.)
mr_colt.