It all started when the child was 10 months old. His parents noticed that the little one gave off a rotten fish smell after eating different types of fish. The unpleasant odor emanated mainly from his head and hands. After removing and then reintroducing the fish, the mother noticed the reappearance of this nauseating odor. The case of this child was described in the journal Journal of Medical Science.
A metabolic disease linked to an enzyme problem
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Doctors who examined the child did not detect a fishy odor during the consultation, because he had not previously consumed this food. They also noted no abnormalities in his neurological development or growth. However, the recurrent appearance of this post-meal odor has directed suspicion towards a rare metabolic disease: trimethylaminuria.
“This disease is characterized by a rotten fish odor from breath, saliva, sweat and urine. It is related to trimethylamine (TMA), a molecule that the body produces when digesting nitrogen-rich foods, such as fish.” first defines Dr Gérald Kierzek, emergency doctor and medical director of Doctissimo.
“In a healthy individual, TMA is transformed into an odorless compound by an enzyme, flavin monooxygenase 3 (FMO3).”
Now you have understood: in people with trimethylaminuria, the FMO3 enzyme does not work properly, which leads to a buildup of trimethylamine in the body and causes that smell.
After a molecular analysis of the FMO3 gene, doctors discovered that the baby had a combination of genetic variants that disrupted the production of the enzyme. Which has been associated with a mild or transient form of the disease.
Fish odor syndrome is a rare condition, with only a few hundred cases described. However, it is probably underdiagnosed.
“It is a rare genetic disease often underdiagnosed because it is little known and also difficult to discuss: the symptoms are shameful, patients hesitate to consult and doctors do not always think about this diagnosis.” indicates Dr. Gérald Kierzek, medical director of Doctissimo.
“The majority of cases remain ignored because the odor is attributed to a hygiene problem, stress or a particular diet, even though it is a medically recognized metabolic disease.”
It is therefore the excretion of this untransformed TMA which poses a problem. “This unpleasant odor is exacerbated by the consumption of certain foods (fish, eggs, legumes), stress, exercise, or hormonal variations. confirms the emergency doctor.
The consequences of this persistent and stubborn odor are significant. “The psychological and social effects include shame, isolation, anxiety, and even some form of depression. emphasizes Dr. Kierzek. Patients often isolate themselves to avoid stigma.
A simple treatment for a cure in children
There is no cure for this disease, but solutions exist to limit the inconvenience. In the child’s case, doctors recommended gradually reintroducing fish into his diet. But also use a neutral pH soap to neutralize odors. Over time, the symptoms subsided. At 19 months, the child ate fish five to six times a week without emitting a bad smell. At 3 years old, the smell never reappeared.
If the disease was transient in this baby, it is because his metabolism was not yet mature enough to allow optimal functioning of the FMO3 enzyme. In adults, the condition is often chronic.
What are the solutions for adults?
For those affected, daily management strategies are possible. It is necessary:
- Adapt the diet by limiting foods rich in choline (eggs, beef liver, soy, etc.) and TMAO (fish, seafood);
- To use specific hygiene products (neutral pH soaps);
- Take activated charcoal or copper chlorophyllin to capture trimethylamine;
- To initiate psychological support in case of suffering.
“A precise diagnosis, based on a urine test after choline intake or via genetic analysis, then provides access to personalized advice and specialized medical support.” concluded Dr. Gérald Kierzek.
