FMO3 bugs, genes and drugs

1. FMO3 bugs, genes and drugs Elizabeth Shephard and Ian Phillips webinar, September 2012

2. FMO3 – mutations can cause Trimethylaminuria, TMAU FMO3 Flavin-containing monooxygenase 3 • FMO3 – is a drug metabolising enzyme

3. BUGSGut microbiome • Human body made up of ~1013 cells • Our intestines contain ~1014 bacterial cells • Gut microbiome is our second genome • Now recognised as a key factor in health and disease

4. Choline bacterial action GUT Trimethylamine (TMA) TMA LIVER FMO3 and trimethylaminuria X FMO3 FMO3 trimethylaminuria TMA N-oxide

5. T201K M405IfsX R51G N114S I199T R238P A52T E314X W388X G475D E32K M82T Q470X G148X R223Q M66I I37T M434I R500X E305X D198E V143E K394KfsX11 K64KfsX2 V58I C197fsX R492W R387L N61S GENES FMO3 mutations causative of TMAuria or implicated in the disorder P153L R308Q 532

6. Amino acids – different ways we name them X = STOP

7. trimethylamine trimethylamine N-oxide P153 Enzyme activity L153 Time (min.) Primary TMAU –genetic basis P (proline) at position 153 – normal enzyme activity L (leucine) at position 153 – enzyme activity severely reduced Nature Genetics, 1997, 17(4): p. 491-4 Dolphin, Janmohamed, Smith, Shephard, Phillips

8. Diagnosis - Urine analysis Measures the concentrations of TMA and TMA N-oxide Results are usually given as a percentage TMA N-oxide X 100 TMA + TMA N-oxide Unaffected = 90 to 100% Mild/moderate’ = 40 to 90 % Severe = less than 40%

9. Secondary TMAU • Acquired TMAU – viral hepatitis • Bacterial overgrowth in intestine • Disease states • Liver and kidney • Transient TMAU • Childhood • Menstruation • Precursor overload

10. Other factors that increase TMA in urine • Urinary tract infection • Bacterial vaginosis • Cervical cancer • Note for these conditions TMA N-oxide:TMA + TMA N-oxide is normal

11. TMAU information links • GeneReview of Trimethylaminuria www.ncbi.nlm.nih.gov/books/NBK1103/ • Clinical Utility Gene Card of Trimethylaminuria www.eurogentest.org Click on trimethylaminuria to download PDF

12. DRUGSFM03 – is a drug metabolising enzyme • Drugs (and other chemicals foreign to the body) have to be removed. • Evolved a defence mechanism to clear foreign chemicals from the body – called detoxification. • Foreign chemicals are changed (metabolised) and then leave the body through the urine, bile and/or feces. • Therapeutic drugs are foreign chemicals (as are e.g. cosmetics and many dietary components).

13. O Detoxification O drug e.g. N-oxide S-oxide FMO3 or other foreign chemical and TMA Liver

14. Pharmacogenetics • How our genes influence the way we handle a drug • Absorption • Distribution • Clearance (e.g. FMO)

15. Why drug metabolism and clearance matters Plasma concentration Plasma concentration Metabolism and drug concentration drops before next dose Limited or no metabolism drug concentration does NOT drop before next dose Potential for adverse effect

16. Examples of FMO3 drug substrates * Impaired metabolism in TMAU individuals

17. Cytochome P450 monooxygenasesCYPs • We have a lot of different CYP genes CYP1 family e.g. CYP1A1, CYP1A2, CYP1B1 CYP2 family e.g. CYP2C19, CYP2D6 CYP3 family e.g. CYP3A4 Many prescription drugs are metabolised by CYP2C19, CYP2D6 and/or CYP3A4

18. Drugs are often metabolised bymore than one CYP and/or FMO • Each enzyme might produce a different drug metabolite OR • Several enzymes might produce the same metabolite

19. CYP1A2 CYP2D6 CYP3A4 imipramine N-oxide Multi-pathway drug metabolism FMOs and CYPs Response to the anti-depressant imipramine imipramine desipramine + metabolites FMO1

20. Drug recycling(retro-reduction) CYP Imipramine Desipramine FMO Several enzymes Imipramine N-oxide

21. Multi-pathway Drug metabolism 80% Pathway A Drug 20% Pathway B 10% Pathway A (impaired) Drug 90% Pathway B

22. E158K E308G 532 FMO3 genotype and treatment of colon polyps with sulindac Gut bacteria FMO3 sulindac sulindacsulphide sulindacsulphoxide prodrug active drug inactive

23. Examples of ‘non-drug’ FMO3 substrates