
This changed gene can’t give instructions for making the FMO3 enzyme. If you have primary trimethylaminuria, it means each parent has one copy of a changed FMO3 gene. When you inherit genes from your parents, you receive two copies of each gene. Without correct instructions, your body can’t make an effective enzyme. This gene carries instructions on making the FMO3 enzyme. Primary trimethylaminuria happens when something changes in the FMO3 gene.

Healthcare providers call this primary trimethylaminuria. Some people may have trimethylaminuria because they have an inherited metabolic condition that blocks the enzyme from breaking down trimethylamine.

But when this enzyme doesn’t work, your trimethlylamine levels build up and make your breath, sweat and pee smell bad. This enzyme breaks down certain chemicals, including trimethlylamine. Normally, your body produces an enzyme called flavin-containing monooxygenase 3 (FMO3). Your intestines produce trimethylamine when you eat some foods, including liver, legumes and eggs. If you have trimethylaminuria, it means your body can’t process a bad-smelling chemical called trimethylamine. People assigned female at birth (AFAB) or more likely to have TMAU than people assigned male at birth (AMAB). Trimethylaminuria is very rare, with healthcare providers reporting a few hundred cases in the 30 years they’ve tracked the condition. But making changes in your diet, using certain soaps and lotions and managing stress can help reduce its symptoms. TMAU may not seem like a major health problem, but people who have trimethylaminuria often struggle with psychological and social issues.

Some illnesses and medications can cause trimethylaminuria. Some people have TMAU due to defective genes passed down from their parents that affect their metabolism. Trimethylaminuria (trī-meth'il-am-i-nyūr'ē-ă) (TMAU) is a very rare condition that makes your sweat, breath, saliva and pee smell like rotten fish or rotten eggs. Avoiding the foods pictured above may help reduce trimethylaminuria symptoms. Trimethylaminuria makes people smell like rotten fish or rotten eggs.
