FMO3 and trimethylaminuria: TMAU is a socially distressing disorder, which results in an odor similar to rotten or decaying fish due to excess TMA being excreted in sweat, urine, breath, and reproductive fluids.2 Individuals with this disorder may suffer from low self‐esteem and depression, and cases of attempted suicide have been reported.1, 13 Affected individuals frequently request information about familial recurrence risk, which poses challenges for risk calculation for cases of less severe TMAU cases particularly if associated with the common FMO3 variants.