The Gene Disorder That Makes You Smell
Amy Norton, The Star, September 16, 2011
For some people with troublesome, unexplained body odor, an uncommon genetic disorder once known as “fish-odor syndrome” may be to blame, according to a study.
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.
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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.
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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.
Studies in the UK have estimated that up to 1 percent of white people carry a flawed copy of FMO3, with some ethnic groups–including people from Ecuador and New Guinea–having a higher rate.
For the current study, Wise and his colleagues looked at how often trimethylaminuria was diagnosed in patients who came to Monell seeking help for unexplained, persistent body odor.
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[Editor’s Note: Studies on racial differences in the prevalence of trimethylaminuria are available here and here.]
