Trimethylaminuria

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Other Names:

TMAU; Fish odor syndrome; Fish malodor syndrome; TMAU; Fish odor syndrome; Fish malodor syndrome; Stale fish syndrome; TMAuria See More

Categories:

Metabolic disorders

Summary Summary

Trimethylaminuria causes the body to produce a fishy odor that is released in the sweat, urine, breath, and reproductive fluids. People with trimethylaminuria are unable to break down trimethylamine. Trimethylamine comes from specific chemicals (choline, carnitine, TMAO) found in certain foods. The excess trimethylamine builds up and is the source of the odor. There are no other physical symptoms from trimethylaminuria, but people with this condition may experience serious psychological and social distress. Trimethylaminuria is due to a FMO3 gene that is not working correctly. It is inherited in an autosomal recessive pattern. It is diagnosed based on the symptoms, clinical exam, urine analysis, and can be confirmed by genetic testing. Treatment for trimethylaminuria mainly includes diet modification, acidic soaps and lotions, and vitamin B12 supplements. Other treatment options include antibiotics, activated charcoal, and probiotics.^[1]^[2]^[3]^[4]^[5]

Last updated: 9/9/2020

Symptoms Symptoms

Trimethylaminuria causes people to have a rotten fish smell. This odor can be different from person to person. The odor may get worse with activities that increase sweating, such as exercise and emotional stress. In females, symptoms may be worse right before and during menstruation, after taking oral contraceptives, or around the time of menopause. In some people, the odor comes and goes, and in others, it is constant.^[1]^[2]

Trimethylaminuria does not cause any other physical symptoms. However, the odor can interfere with many aspects of daily life, leading to social and psychological problems.^[2]^[3]

Last updated: 9/9/2020

This table lists symptoms that people with this disease may have. For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. This information comes from a database called the Human Phenotype Ontology (HPO) . The HPO collects information on symptoms that have been described in medical resources. The HPO is updated regularly. Use the HPO ID to access more in-depth information about a symptom.

Showing of 9 |

Medical Terms	Other Names	Learn More: HPO ID
Percent of people who have these symptoms is not available through HPO
Anemia	Low number of red blood cells or hemoglobin	0001903
Autosomal recessive inheritance		0000007
Depressivity	Depression	0000716
Hypertension		0000822
Neutropenia	Low blood neutrophil count Low neutrophil count [ more ]	0001875
Recurrent pneumonia		0006532
Splenomegaly	Increased spleen size	0001744
Tachycardia	Fast heart rate Heart racing Racing heart [ more ]	0001649
Trimethylaminuria	High urine trimethylamine levels	0003614

Showing of 9 |

Do you have more information about symptoms of this disease? We want to hear from you.

Last updated: 2/1/2021

Cause Cause

Trimethylaminuria is caused by the FMO3 gene not working correctly. DNA changes known as pathogenic variants are responsible for making genes work incorrectly or sometimes, not at all.^[1]^[2]

Last updated: 9/9/2020

Inheritance Inheritance

Trimethylaminuria is inherited in an autosomal recessive pattern.^[1] Some conditions are inherited in an autosomal recessive pattern. All individuals inherit two copies of each gene. Autosomal means the gene is found on one of the numbered chromosomes found in both sexes. Recessive means that both copies of the responsible gene must be altered to have the condition.

People with autosomal recessive conditions inherit one alteration from each of their parents. The parents, who each have one gene alteration, are known as carriers. Carriers of an autosomal recessive condition typically do not have any signs or symptoms (they are unaffected). In some cases, carriers of trimethylaminuria may have mild or occasional symptoms. When two carriers of an autosomal recessive condition have children, there is a 25% (1 in 4) chance to have a child with the condition.

Last updated: 9/9/2020

Diagnosis Diagnosis

Trimethylaminuria is diagnosed based on the symptoms, a clinical exam, and a test to measure the level of trimethylamine in the urine. Genetic testing can also help confirm the diagnosis.^[1]^[2]

Guidelines for diagnosing trimethylaminuria have been published.^[5]

Last updated: 9/9/2020

Testing Resources

The Biochemical Genetics Laboratory at Children's Hospital Colorado does specialized testing on urine to look for levels of trimethylamine. For information about testing, please contact Lab Client Services at labclientservices@childrenscolorado.org or at 720-777-6711. The lab encourages using the email address instead of calling so they can give you all the materials and information you need. To arrange the test itself, the lab must work directly with your primary care provider (PCP).
The Genetic Testing Registry (GTR) provides information about the genetic tests for this condition. The intended audience for the GTR is health care providers and researchers. Patients and consumers with specific questions about a genetic test should contact a health care provider or a genetics professional.

Treatment Treatment

Treatment for trimethylaminuria is focused on removing and preventing the bad odor. Options for treatment include diet modification, vitamin B12 (riboflavin) supplements, antibiotic treatment, and probiotics. Other supplements such as activated charcoal can help remove extra trimethylamine from the body. In addition, some people with trimethylaminuria may benefit from behavioral counseling.^[2]^[3]

Specialists involved in the care of someone with trimethylaminuria may include:^[1]

Nutritionist
Medical geneticist
Pharmacist
Psychologist/psychiatrist

Last updated: 9/9/2020

Statistics Statistics

The exact number of people with trimethylaminuria is unknown. It has been estimated that about 0.5 -1% of people in the British population are carriers for trimethylaminuria. A carrier has one copy of a gene variant for trimethylaminuria.^[1]^[4]

Last updated: 9/9/2020

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Find a Specialist Find a Specialist

If you need medical advice, you can look for doctors or other healthcare professionals who have experience with this disease. You may find these specialists through advocacy organizations, clinical trials, or articles published in medical journals. You may also want to contact a university or tertiary medical center in your area, because these centers tend to see more complex cases and have the latest technology and treatments.

If you can’t find a specialist in your local area, try contacting national or international specialists. They may be able to refer you to someone they know through conferences or research efforts. Some specialists may be willing to consult with you or your local doctors over the phone or by email if you can't travel to them for care.

You can find more tips in our guide, How to Find a Disease Specialist. We also encourage you to explore the rest of this page to find resources that can help you find specialists.

Healthcare Resources

To find a medical professional who specializes in genetics, you can ask your doctor for a referral or you can search for one yourself. Online directories are provided by the American College of Medical Genetics and the National Society of Genetic Counselors. If you need additional help, contact a GARD Information Specialist. You can also learn more about genetic consultations from MedlinePlus Genetics.

Organizations Organizations

Support and advocacy groups can help you connect with other patients and families, and they can provide valuable services. Many develop patient-centered information and are the driving force behind research for better treatments and possible cures. They can direct you to research, resources, and services. Many organizations also have experts who serve as medical advisors or provide lists of doctors/clinics. Visit the group’s website or contact them to learn about the services they offer. Inclusion on this list is not an endorsement by GARD.

Social Networking Websites

RareConnect has an online community for patients and families with this condition so they can connect with others and share their experiences living with a rare disease. The project is a joint collaboration between EURORDIS (European Rare Disease Organisation) and NORD (National Organization for Rare Disorders).

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Living With Living With

Living with a genetic or rare disease can impact the daily lives of patients and families. These resources can help families navigate various aspects of living with a rare disease.

Community Resources

The Job Accommodation Network (JAN) has information on workplace accommodations and disability employment issues related to this condition. JAN is a service of the Office of Disability Employment Policy in the U.S. Department of Labor.

Learn More Learn More

These resources provide more information about this condition or associated symptoms. The in-depth resources contain medical and scientific language that may be hard to understand. You may want to review these resources with a medical professional.

Where to Start

Genetics Home Reference (GHR) contains information on Trimethylaminuria. This website is maintained by the National Library of Medicine.
The National Human Genome Research Institute's (NHGRI) website has an information page on this topic. NHGRI is part of the National Institutes of Health and supports research on the structure and function of the human genome and its role in health and disease.
The National Organization for Rare Disorders (NORD) has a report for patients and families about this condition. NORD is a patient advocacy organization for individuals with rare diseases and the organizations that serve them.

In-Depth Information

GeneReviews provides current, expert-authored, peer-reviewed, full-text articles describing the application of genetic testing to the diagnosis, management, and genetic counseling of patients with specific inherited conditions.
The Monarch Initiative brings together data about this condition from humans and other species to help physicians and biomedical researchers. Monarch’s tools are designed to make it easier to compare the signs and symptoms (phenotypes) of different diseases and discover common features. This initiative is a collaboration between several academic institutions across the world and is funded by the National Institutes of Health. Visit the website to explore the biology of this condition.
Online Mendelian Inheritance in Man (OMIM) is a catalog of human genes and genetic disorders. Each entry has a summary of related medical articles. It is meant for health care professionals and researchers. OMIM is maintained by Johns Hopkins University School of Medicine.
Orphanet is a European reference portal for information on rare diseases and orphan drugs. Access to this database is free of charge.
PubMed is a searchable database of medical literature and lists journal articles that discuss Trimethylaminuria. Click on the link to view a sample search on this topic.

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References References

Phillips I, Shephard E. Primary trimethylaminuria. GeneReviews. Updated Oct 2015; http://www.ncbi.nlm.nih.gov/books/NBK1103/.
Bouchemal N, Ouss L, Brassier A, et al. Diagnosis and phenotypic assessment of trimethylaminuria, and its treatment with riboflavin: H NMR spectroscopy and genetic testing. Orphanet J Rare Dis. 2019; 14(1):222. https://pubmed.ncbi.nlm.nih.gov/31533761.
Schmidt AC, Leroux JC. Treatments of trimethylaminuria: where we are and where we might be heading. Drug Discov Today. Jun, 2020; S1359-6446(20)30254-3. https://pubmed.ncbi.nlm.nih.gov/32615074.
Doyle S, O'Byrne JJ, Nesbitt M, et al. The genetic and biochemical basis of trimethylaminuria in an Irish cohort. JIMD Rep. 2019; 47(1):35-40. https://pubmed.ncbi.nlm.nih.gov/31240165.
Chalmers RA, Bain MD, Michelakakis H, Zschocke J, Iles RA. Diagnosis and management of trimethylaminuria (FMO3 deficiency) in children. J Inherit Metab Dis. Feb 2006; 29(1):162-72. https://pubmed.ncbi.nlm.nih.gov/16601883.