What Is Fish Odor Syndrome?

Trimethylamine (TMA) is an amine with the smell of rancid fish, especially in egg yolks, beans, and saltwater fish; Trimethylaminuria (trimethylamine) Patients with urinary disease, because of the inability to metabolize TMA, causing the smell of TMA from breathing, urine, sweat and glandular secretions, hence the name. Patients with this disease often have odors caused by abnormal TMA metabolism (not only fish odor) after birth, but have consumed TMA precursors; such as: egg yolk, animal offal (liver and kidney), pods, soybeans, and When saltwater fish, the taste will be more exacerbated. The taste of TMA may be more pronounced after exercise or when the mood is low, and before and after puberty, menstruation and menopause in female patients.

Stinkfish TMA comes from common foods. It is catalyzed by the FMO3 enzyme (flavin-containing monooxygenase 3) during liver oxidation (N-oxygenation), and can be smoothly metabolized into odorless trimethylamine N-oxide (TMAO). Due to the defect of the flavin-containing monooxygenase 3 gene at the 23-25 position of the long arm of the first pair of chromosomes of the patient, the activity of the FMO3 enzyme is insufficient, and TMA cannot be metabolized smoothly.

In addition to the unpleasant smell, patients with this disease usually have normal intelligence and good health, but they often hinder the development of learning and social activities because of the smell of fish.

Some patients experience tachycardia and hypertension after eating tyramine foods (cheese). In addition, it may be because of the abnormal metabolism of amines that it affects the chemical action in the brain, which may cause mental disorders such as depression or depression.

Fish smell is a rare disease caused by mutations in a specific gene. It prevents the body from breaking down a compound called trimethylamine. Trimethylamine can make fish smell fishy; when it accumulates in the body, it will be released through breathing, urine and sweat, making patients smell like fishy. This scent is unacceptable and often leads to depression or social isolation in patients.

The test methods are: 1. The concentration of TMA in urine can be quantitatively detected by liquid chromatography; usually, the TMA concentration of patients will be higher than 18 mol / mmol creatinine. 2. Nuclear magnetic resonance spectroscopy analysis to determine the values of TMA and TMAO in urine to further obtain the results of TMA% (TMA + TMAO). Generally, the normal value is 2-9%, while the value of male patients may be as high as 59-89 %, Female patients are 46-90%. 3. Oral TMA is used for tolerance test, and then the urine TMA value is measured to evaluate its metabolism.

In laboratory related examinations, liquid chromatography can be used to quantitatively detect the TMA concentration in urine; usually, the TMA concentration of patients will be higher than 18 mol / mmol creatinine.

For further examination, the value of TMA and TMAO in urine can be determined by NMR spectroscopy to further obtain the result of TMA% (TMA + TMAO). Generally, the normal value is 2-9%. The value can be as high as 59-89% for male patients and 46-90% for female patients.

In the detection of cause-causing patients, oral TMA can be used to perform an oral trimethylamine loading test, and then the value of TMA in urine can be measured to evaluate its metabolic situation.

In addition, FMO3 gene detection can be performed through molecular biotechnology, but this test is mostly research-oriented and only a few specific laboratories provide it.

In daily life, patients can reduce the production of body odor through the following diet and life precautions:

1. In food, avoid foods that produce TMA precursors; in choline foods, avoid eating eggs (which are egg yolks), animal offal (liver and kidney), legumes, beans ( (Such as soybeans), nuts (such as peanuts), cabbage vegetables (cauliflower, cabbage, cabbage), spinach, lettuce, beer yeast, whole grains, and saltwater fish and other foods, while the lower TMA content of freshwater fish is usually less restrictive . In addition, you should avoid eating nutritional supplements such as lecithin and fish oil.

2. You can take riboflavin to increase the remaining FMO3 enzyme activity, and you can eat activated carbon and chlorophyll preparations to reduce the accumulation of TMA in the intestine.

3. In addition, antibiotics can be used to inhibit bacteria in the intestine, and laxatives can be used to reduce TMA in the intestine if necessary (if there is an important social event).

4. Weak acid (pH 5.5 ~ 6.5) soap and lotion can be used to reduce the unpleasant odor on the skin. ^[1]

Although there will be no other adverse symptoms, often because of the odor emitted from the body, it is easy for the case to receive different perspectives and even rejection in learning and social situations, and it is easy to adversely affect the psychological development. Therefore, early communication and pre-education and advocacy are important pre-school preparations. Through proper communication and explanation, to increase the awareness of the peers in school or society about illness, and to replace prejudice with understanding, the harm to the case can be minimized, which helps the case's learning and social development.

It is a recessive inheritance of chromosomes. If the parent is a carrier, it means that each chromosome has a FMO3-deficient gene. Because the gene on the other chromosome is normal, it will not develop the disease, but the next generation does not distinguish between men and women. There is a 25% chance that the patient will be born, a 50% chance is that the same cause as the parents, and a 25% chance is normal.

It is estimated that the incidence of this disease in the United States is less than one in 200,000.

This disease has been listed as a rare disease in China. It is estimated that the domestic incidence should be less than 1 in 10,000.

According to the study by Mitchell et al (1997), the cause of this disease varies from country to country; the cause of the white British population is about 0.5% -1.0%, the Jordanian population is 1.7%, and the Ecuadorian population is 3.8% The banding rate of the New Guinea ethnic group may be as high as 11.0%.