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Trimethylaminuria via the FMO3 Gene

Summary and Pricing

Test Method

Exome Sequencing with CNV Detection
Test Code Test Copy GenesTest CPT Code Gene CPT Codes Copy CPT Codes Base Price
FMO3 81479 81479,81479 $990
Test Code Test Copy Genes Test CPT Code Gene CPT Codes Copy CPT Code Base Price
8503FMO381479 81479,81479 $990 Order Options and Pricing

Pricing Comments

Our favored testing approach is exome based NextGen sequencing with CNV analysis. This will allow cost effective reflexing to PGxome or other exome based tests. However, if full gene Sanger sequencing is desired for STAT turnaround time, insurance, or other reasons, please see link below for Test Code, pricing, and turnaround time information. If the Sanger option is selected, CNV detection may be ordered through Test #600.

An additional 25% charge will be applied to STAT orders. STAT orders are prioritized throughout the testing process.

Click here for costs to reflex to whole PGxome (if original test is on PGxome Sequencing platform).

Click here for costs to reflex to whole PGnome (if original test is on PGnome Sequencing platform).

The Sanger Sequencing method for this test is NY State approved.

For Sanger Sequencing click here.

Turnaround Time

3 weeks on average for standard orders or 2 weeks on average for STAT orders.

Please note: Once the testing process begins, an Estimated Report Date (ERD) range will be displayed in the portal. This is the most accurate prediction of when your report will be complete and may differ from the average TAT published on our website. About 85% of our tests will be reported within or before the ERD range. We will notify you of significant delays or holds which will impact the ERD. Learn more about turnaround times here.

Targeted Testing

For ordering sequencing of targeted known variants, go to our Targeted Variants page.


Genetic Counselors


  • McKenna Kyriss, PhD

Clinical Features and Genetics

Clinical Features

Trimethylaminuria (TMAU, OMIM 602079), also called fish-odor syndrome, is a metabolic disease that is due to the malfunction of the hepatic enzyme flavin-containing monooxygenase 3 (FMO3). The FMO3 enzyme catalyzes the oxidation of fishy-smelling trimethylamine, found in foods rich in choline and carnitine, into odorless trimethylamine-N-oxide. In patients with TMAU, FMO3 malfunction results in the accumulation of trimethylamine in the body and subsequent release in the breath, saliva, sweat, urine, and other body secretions (Cashman et al. Curr Drug Metab 4:151-170, 2003). Symptoms are intermittent and usually begin in childhood. They are exacerbated by environmental factors including diet, emotional stress, and physical activity; they may lead to psychological problems (Rehman Postgrad Med J 75:451-452, 1999). TMAU is more common and more pronounced in women than men.


Trimethylaminuria (TMAU) is inherited in an autosomal recessive manner and is caused by variants in the FMO3 gene (Dolphin et al. Nat Genet 17:491-494, 1997). To date, about 50 FMO3 variants have been reported. The majority of variants are missense. Other rare variants include nonsense, splicing, and small and large deletions. Homozygous variants in families with or without history of consanguinity and compound heterozygous variants were detected. Heterozygous carriers may develop a transient form of the disease (Allerston Mol Genet Metab 98:198-202, 2009). The FMO3 gene encodes the flavin-containing monooxygenase 3, one of several enzymes involved in the metabolism of chemical compounds that contain nitrogen, sulfur, or phosphorous.

Clinical Sensitivity - Sequencing with CNV PGxome

Unknown at this time.

Testing Strategy

This test provides full coverage of all coding exons of the FMO3 gene plus 10 bases of flanking noncoding DNA in all available transcripts along with other non-coding regions in which pathogenic variants have been identified at PreventionGenetics or reported elsewhere. We define full coverage as >20X NGS reads or Sanger sequencing. PGnome panels typically provide slightly increased coverage over the PGxome equivalent. PGnome sequencing panels have the added benefit of additional analysis and reporting of deep intronic regions (where applicable).

Dependent on the sequencing backbone selected for this testing, discounted reflex testing to any other similar backbone-based test is available (i.e., PGxome panel to whole PGxome; PGnome panel to whole PGnome).

Indications for Test

Patients with strong body odor and increased free trimethylamine excretion in urine, with reduced trimethylamine-N-oxide. This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in FMO3.


Official Gene Symbol OMIM ID
FMO3 136132
Inheritance Abbreviation
Autosomal Dominant AD
Autosomal Recessive AR
X-Linked XL
Mitochondrial MT


Name Inheritance OMIM ID
Trimethylaminuria AR 602079


  • Allerston, C. K., et.al. (2009). "A novel mutation in the flavin-containing monooxygenase 3 gene (FMO3) of a Norwegian family causes trimethylaminuria." Mol Genet Metab 98(1-2): 198-202. PubMed ID: 19577495
  • Cashman, J. R., et.al. (2003). "Biochemical and clinical aspects of the human flavin-containing monooxygenase form 3 (FMO3) related to trimethylaminuria." Curr Drug Metab 4(2): 151-70. PubMed ID: 12678693
  • Dolphin, C. T., et.al. (1997). "Missense mutation in flavin-containing mono-oxygenase 3 gene, FMO3, underlies fish-odour syndrome." Nat Genet 17(4): 491-4. PubMed ID: 9398858
  • Rehman, H. U. (1999). "Fish odor syndrome." Postgrad Med J 75(886): 451-2. PubMed ID: 10646019


Ordering Options

We offer several options when ordering sequencing tests. For more information on these options, see our Ordering Instructions page. To view available options, click on the Order Options button within the test description.

myPrevent - Online Ordering

  • The test can be added to your online orders in the Summary and Pricing section.
  • Once the test has been added log in to myPrevent to fill out an online requisition form.
  • PGnome sequencing panels can be ordered via the myPrevent portal only at this time.

Requisition Form

  • A completed requisition form must accompany all specimens.
  • Billing information along with specimen and shipping instructions are within the requisition form.
  • All testing must be ordered by a qualified healthcare provider.

For Requisition Forms, visit our Forms page

If ordering a Duo or Trio test, the proband and all comparator samples are required to initiate testing. If we do not receive all required samples for the test ordered within 21 days, we will convert the order to the most effective testing strategy with the samples available. Prior authorization and/or billing in place may be impacted by a change in test code.

Specimen Types

Specimen Requirements and Shipping Details

PGxome (Exome) Sequencing Panel

PGnome (Genome) Sequencing Panel

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View Ordering Instructions

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2) Select Additional Test Options

No Additional Test Options are available for this test.

Note: acceptable specimen types are whole blood and DNA from whole blood only.
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