The condition, known clinically as trimethylaminuria, is caused by emitting excessive amounts of the compound trimethylamine (TMA). TMA is produced when people digest foods rich in a substance called choline -- including saltwater fish, eggs, liver and certain legumes, such as soy and kidney beans.
"Individuals with the metabolic disorder trimethylaminuria may sporadically produce malodors despite good hygiene," wrote study leader Paul Wise, at Monell Chemical Senses Center in Philadelphia, in the American Journal of Medicine.
"The psychosocial impact of trimethylaminuria may be considerable. However, trimethylaminuria is difficult to diagnose without specialized tests."
Trimethylaminuria is caused by defects in a gene known as FMO3, which hinder the body's ability to metabolize TMA and turn it into odor-free compounds.
TMA itself has a strong fishy smell, but only about 10 to 15 percent of people with trimethylaminuria have that specific malodor, which may make it tougher to get a diagnosis.
For someone to have the disorder, he or she must inherit a defective copy of the FMO3 gene from both parents, who themselves would be unaffected "carriers." Of course, if either of the parents had the disorder, they would also pass it on.
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