This is a respected book on the drug metabolizing enzymes (1999). The chapter on Flavin Mono Oxygenase enzymes is written by the well known respected FMO expert, Dr John Cashman of HBRI. Given that little research goes on with regards FMO, but more research has been done recently, it is unclear how up to date the chapter will be.
Of interest is where Dr Cashman says lowered FMO function is likely to be associated with other metabolic conditions since this doesn't seem to be the general impression given from medical websites/books. Google books has pages missing, but you can get a general sense of the enzyme from the chapter.
Handbook of Drug Metabolism (1999)
Edited by Thomas F. Woolf
Finally, the role of FMO in human disease conditions is certain to be studied in increasing detail in the future. The abrogation of human FMO3 has been associated with trimethylaminuria, but it is likely the variant forms of FMO are associated with other abnormal metabolic conditions because trimethylaminuria patients appear to suffer from a number of other disease states as well. With the emergence of new and sensitive selective molecular probe of human FMO, it is possible that a role of FMO in human disease conditions will be clarified...
http://books.google.com - the chapter on FMO enzymes from the Handbook of Drug Metabolism