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Genetic and Rare Diseases Information Center (GARD)

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Other Names for this Disease
  • Fish malodor syndrome
  • Fish odor syndrome
  • Stale fish syndrome
  • TMAU
  • TMAuria
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How is trimethylaminuria inherited?

Trimethylaminuria is usually inherited in an autosomal recessive pattern, which means that which means that both copies of the gene in each cell have mutations in order for a person to have symptoms. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene and are referred to as "carriers" of the condition. .[1]

Since trimethylaminuria usually requires two mutations to cause symptoms, typically neither parent of an individual with trimethylaminuria has any symptoms.   Occasionally, however, carriers of one copy of an FMO3 mutation may experience mild symptoms of trimethylaminuria or have temporary episodes of fish-like odor.[1]

When two people who are carriers of an autosomal recessive condition have a child, there is a 25% (1 in 4) chance that the child will have the condition, a 50% (1 in 2) chance that the child will be a carrier like each of the parents, and a 25% (1 in 4) chance that the child will not have the condition and not be a carrier.
Last updated: 1/27/2014

  1. Learning about Trimethylaminuria. National Human Genome Research Institute Web site. July 20, 2011; Accessed 1/27/2014.
  2. Trimethylaminuria. Genetics Home Reference Web site. January 2013; Accessed 1/27/2014.
  3. Phillips IR, Shephard EA. Trimethylaminuria. GeneReviews. April 19, 2011; Accessed 1/27/2014.