There is no known cure or treatment for the disorder.

The metabolic and clinical manifestations of TMAU are generally regarded as benign, as there is no associated organ dysfunction. This

designation, and the fact that the condition is often unrecognised by doctors, can have important ramifications including missed or delayed diagnosis.

Affected individuals experience shame and embarrassment, fail to maintain relationships, avoid contact with people who comment on their condition, and are obsessive about masking the odour with hygiene products and even smoking. The malodorous aspect can have serious and destructive effects on schooling, personal life, career and relationships, resulting in social isolation, low self-esteem, depression, paranoid behaviour, and suicide. Delayed diagnosis, body odour and the lack of cure may lead to psychosocial issues. When the condition is suspected or known to occur in a family, genetic testing can be helpful in identifying the specific individuals who have or carry the disorder.

Ways of reducing the fishy odor may include:

- Avoiding foods such as egg yolks, legumes, red meats, fish, beans and other foods that contain choline, carnitine, nitrogen, sulfur and lecithin

- Taking low doses of antibiotics such as neomycin and metronidazole in order to reduce the amount of bacteria in the gut

- Using slightly acidic detergent with a pH between 5.5 and 6.5

Additionally, at least one study has suggested that daily intake of the supplements activated charcoal and copper chlorophyllin may improve the quality of life of individuals afflicted with TMAU by helping their bodies to oxidize and convert TMA to the odorless "N"-oxide (TMAO) metabolite. Study participants experienced subjective reduction in odor as well as objective reduction in TMA and increase in TMAO concentration measured in their urine. The study found that:

- 85% of test participants experienced complete loss of detectable "fishy" odor

- 10% experienced some reduction in detectable odor

- 5% did not experience any detectable odor reduction

Most cases of trimethylaminuria appear to be inherited in an autosomal recessive pattern, which means two copies of the gene in each cell are altered. The parents of an individual with an autosomal recessive disorder are both carriers of one copy of the altered gene. Carriers may have mild symptoms of trimethylaminuria or experience temporary episodes of fish-like body odor.

Mutations in the "FMO3" gene, which is found on the long arm of chromosome 1, cause trimethylaminuria. The "FMO3" gene makes an enzyme that breaks down nitrogen-containing compounds from the diet, including trimethylamine. These compounds are produced by bacteria in the intestine as they digest proteins from eggs, meat, soy, and other foods. Normally, the "FMO3" enzyme converts fishy-smelling trimethylamine into trimethylamine "N"-oxide which has no odor. If the enzyme is missing or its activity is reduced because of a mutation in the "FMO3" gene, trimethylamine is not broken down and instead builds up in the body. As the compound is released in a person's sweat, urine, and breath, it causes the strong odor characteristic of trimethylaminuria. Researchers believe that stress and diet also play a role in triggering symptoms.

There are more than 40 known mutations associated with TMAU. Loss-of-function mutations, nonsense mutations, and missense mutations are three of the most common. Nonsense and missense mutations cause the most severe phenotypes.

Although "FMO3" mutations account for most known cases of trimethylaminuria, some cases are caused by other factors. A fish-like body odor could result from an excess of certain proteins in the diet or from an increase in bacteria in the digestive system. A few cases of the disorder have been identified in adults with liver damage caused by hepatitis.

In 2007 the evolution of the "FMO3" gene was studied, including the evolution of some mutations associated with TMAU.

A 2011 review of 176 cases found that diagnoses made early in life (within a few days of birth) were associated with more severe disease and a mortality of 33%. Children diagnosed later, and who had milder symptoms, showed a lower mortality rate of ~3%.

For women with phenylketonuria, it is important for the health of their children to maintain low Phe levels before and during pregnancy. Though the developing fetus may only be a carrier of the PKU gene, the intrauterine environment can have very high levels of phenylalanine, which can cross the placenta. The child may develop congenital heart disease, growth retardation, microcephaly and intellectual disability as a result. PKU-affected women themselves are not at risk of additional complications during pregnancy.

In most countries, women with PKU who wish to have children are advised to lower their blood Phe levels (typically to between 2 and 6 mg/dL) before they become pregnant, and carefully control their levels throughout the pregnancy. This is achieved by performing regular blood tests and adhering very strictly to a diet, in general monitored on a day-to-day basis by a specialist metabolic dietitian. In many cases, as the fetus' liver begins to develop and produce PAH normally, the mother's blood Phe levels will drop, requiring an increased intake to remain within the safe range of 2–6 mg/dL. The mother's daily Phe intake may double or even triple by the end of the pregnancy, as a result. When maternal blood Phe levels fall below 2 mg/dL, anecdotal reports indicate that the mothers may suffer adverse effects, including headaches, nausea, hair loss, and general malaise. When low phenylalanine levels are maintained for the duration of pregnancy, there are no elevated levels of risk of birth defects compared with a baby born to a non-PKU mother.

Isovaleric acidemia is estimated to affect at least 1 in 250,000 births in the United States.

Maple syrup urine disease (MSUD) is a rare, inherited metabolic disorder. Its prevalence in the United States population is approximately 1 newborn out of 180,000 live births. However, in populations where there is a higher frequency of consanguinity, such as the Mennonites in Pennsylvania or the Amish, the frequency of MSUD is significantly higher at 1 newborn out of 176 live births. In Austria, 1 newborn out of 250,000 live births inherits MSUD. It also is believed to have a higher prevalence in certain populations due in part to the founder effect since MSUD has a much higher prevalence in children of Amish, Mennonite, and Jewish descent.

Control of metabolism is vital during pregnancy of women with MSUD. To prevent detrimental abnormalities in development of the embryo or fetus, dietary adjustments should be made and plasma amino acid concentrations of the mother should be observed carefully and frequently. Amino acid deficiency can be detected through fetal growth, making it essential to monitor development closely.

The average number of new cases of PKU varies in different human populations. United States Caucasians are affected at a rate of 1 in 10,000. Turkey has the highest documented rate in the world, with 1 in 2,600 births, while countries such as Finland and Japan have extremely low rates with fewer than one case of PKU in 100,000 births. A 1987 study from Slovakia reports a Roma population with an extremely high incidence of PKU (one case in 40 births) due to extensive inbreeding. It is the most common amino acid metabolic problem in the United Kingdom.

Kleefstra syndrome affects males and females equally and approximately, 75% of all documented cases are caused by Eu-HMTase1 disruptions while only 25% are caused by 9q34.3 deletions. There are no statistics on the effect the disease has on life expectancy due to the lack of information available.

As many as 90% of Americans and 92% of teenagers use antiperspirants or deodorants. In 2014, the global market for deodorants was estimated at 13.00 billion USD with a compound annual growth rate of 5.62% between 2015 and 2020.

Body odor may be reduced or prevented or even aggravated by using deodorants, antiperspirants, disinfectants, underarm liners, triclosan, special soaps or foams with antiseptic plant extracts such as ribwort and liquorice, chlorophyllin ointments and sprays topically, and chlorophyllin supplements internally. Although body odor is commonly associated with hygiene practices, its presentation can be affected by changes in diet as well as the other factors.

Renal failure is the major cause of morbidity and mortality in complete LCAT deficiency, while in partial deficiency (fish eye disease) major cause of morbidity is visual impairment due to corneal opacity. These patients have low HDL cholesterol but surprisingly premature atherosclerosis is not seen. However, there are some reported cases.

While only a few adults have been reported with 2q37 microdeletion syndrome, it is predicted that this number will rise as various research studies continue to demonstrate that most with the disorder do not have a shortened life span.

Fancy goldfish are among the fish most commonly affected by this disorder. The disease may be caused by intestinal parasites or by constipation induced by high nitrate levels from over feeding.

Due to its recent discovery, there are currently no existing treatments for Kleefstra syndrome.

A remedy, which can work within hours, perhaps by countering constipation, is to feed green pea to affected fish. Fish surgeons can also adjust the buoyancy of the fish by placing a stone in the swim bladder or performing a partial removal of the bladder.

Type 1 tyrosinemia, also known as hepatorenal tyrosinemia or tyrosinosis, is the most severe form of tyrosinemia, a buildup of too much of the amino acid tyrosine in the blood and tissues due to an inability to metabolize it. It is caused by a deficiency of the enzyme fumarylacetoacetate hydrolase.

"Hole in the head can be reversed by removing all activated carbon and conducting large percentage water changes. Greater than 90% water changes may need to be done to reduce the effects of activated carbon. More commonly, cures are made by moving the fish to a new aquarium that has never had fish develop HLLE in it.

The most accepted cause that has the most evidence is the use of activated carbon in closed aquarium ecosystems.

A similar study also points to carbon as a cause of HLLE

Many other causes have been suggested, but have not been substantiated by any peer-reviewed studies.

Lecithin cholesterol acyltransferase deficiency (LCAT deficiency) is a disorder of lipoprotein metabolism. The disease has two forms: Familial LCAT deficiency, in which there is complete LCAT deficiency, and Fish-eye disease, in which there is a partial deficiency.

Lecithin cholesterol acyltransferase catalyzes the formation of cholesterol esters in lipoproteins.

The disruption of olfaction and potential effects to survival and reproductive success at environmentally-relevant concentrations metals, pesticides or surfactants have implications for fish and salmon recovery because these are commonly found in western United States streams. Conventional, acute and chronic toxicity testing do not explicitly address nervous system function and underestimate thresholds for toxicity in salmonids. Since these effects are not explicitly looked at during studies they oftentimes can go unnoticed. Olfactory toxicity occurring at environmentally relevant concentrations can induce reduction to food odor attraction and predator scent or alarm response pheromones can cause major problems with survivorship. Olfactory toxicity can also affect the ability of anadromous fish to find their natal stream causing them to stray to other streams.

The primary treatment for type 1 tyrosinemia is nitisinone (Orfadin) and restriction of tyrosine in the diet. Nitisinone inhibits the conversion of 4-OH phenylpyruvate to homogentisic acid by 4-Hydroxyphenylpyruvate dioxygenase, the second step in tyrosine degradation. By inhibiting this enzyme, the accumulation of the fumarylacetoacetate is prevented. Previously, liver transplantation was the primary treatment option and is still used in patients in whom nitisinone fails.

Therapy can help developmental delays, as well as physiotherapy for the low muscle tone. Exercise and healthy eating can reduce weight gain. Treatments are available for seizures, eczema, asthma, infections, and certain bodily ailments.

Wolf–Hirschhorn syndrome (WHS), also known as chromosome deletion Dillan 4p syndrome, Pitt–Rogers–Danks syndrome (PRDS) or Pitt syndrome, was first described in 1961 by Americans Herbert L. Cooper and Kurt Hirschhorn and, thereafter, gained worldwide attention by publications by the German Ulrich Wolf, and Hirschhorn and their co-workers, specifically their articles in the German scientific magazine "Humangenetik". It is a characteristic phenotype resulting from a partial deletion of chromosomal material of the short arm of chromosome 4 (del(4p16.3)).

Avoidance behavior exhibited by fish is species specific, Whitefish ("C. clupeaformis") showed a preference toward SLS at a concentration of 0.1 mg/L while rainbow trout ("Oncorhynchus mykiss") and common carp ("Cyprinus carpio") showed an avoidance response at a concentration of 0.01 ug/L. Past studies are difficult to compare due to differences in test and exposure conditions.