The gene involved in halitosis

the gene involved in extra-oral halitosis

The FMO3 gene plays a crucial role in extra-oral halitosis, particularly in a condition known as trimethylaminuria (TMAU), also referred to as fish odour syndrome (not a nice name). Here’s an in-depth look at the role of the FMO3 gene and its connection to extra-oral halitosis.

FMO3 Gene & Its Function

The FMO3 gene encodes for the enzyme flavin-containing monooxygenase 3 (FMO3).

This enzyme is responsible for the oxidation of trimethylamine (TMA), a compound produced during the digestion of certain foods that contain choline and carnitine (found in foods like eggs, liver, legumes, and fish).

Normally, FMO3 converts TMA, which has a strong fishy odour, into the odourless compound trimethylamine N-oxide (TMAO).

Trimethylaminuria (TMAU)

Trimethylaminuria is a genetic disorder caused by mutations in the FMO3 gene. These mutations can lead to a reduced or absent activity of the FMO3 enzyme.

As a result, the body is unable to efficiently convert TMA into TMAO. Consequently, TMA accumulates in the body and is released in bodily fluids, including the breath, sweat, urine and saliva, leading to a strong, unpleasant odour.

Genetic Basis

Trimethylaminuria can be inherited in an autosomal recessive manner, meaning that an individual must inherit two defective copies of the FMO3 gene (one from each parent) to manifest the disorder. Carriers, who have only one defective copy, typically do not exhibit symptoms but can pass the gene to their offspring.

Symptoms and Impact

The primary symptom of trimethylaminuria is the persistent bad odour, which can vary in intensity and can be influenced by factors like diet, hormonal changes, stress and overall health. This condition can have a significant psychological and social impact, leading to anxiety, depression, and social isolation due to the distress and embarrassment caused by the persistent odour.

Management

Various management strategies can help reduce odour

• Dietary Modifications – Reducing intake of TMA precursors by avoiding foods rich in choline and carnitine

• Supplements – Activated charcoal and copper chlorophyllin may help bind TMA in the gut and reduce its absorption