To the Editor: We report the case of a 41-year-old woman who sought medical opinion about an unpleasant body odour, first noticed when she was 7 years old. After experiencing ridicule, distress, shame, anxiety and low self-esteem during her school years, she first consulted a doctor about the problem at the age of 17 years, then again 2 years later, followed by a further four doctors over the next 20 years. All dismissed her concerns, and she was repeatedly told that she had a hygiene neurosis. Investigations and treatments during this time included being “sniffed”, vaginal swabs and vaginal cauterisation. Finally, a general practitioner referred her to a dermatologist, who consulted a microbiologist, and the diagnosis of trimethylaminuria (TMAU), or fish malodour syndrome, was confirmed by urinalysis. Now having a name for her condition, she found an Internet-based support foundation and referred herself for genetic counselling.

TMAU is caused by an enzyme deficiency due to mutations in the flavin-containing mono-oxygenase 3 (FMO3) gene,1 resulting in excess excretion of trimethylamine in urine, sweat and breath. It is diagnosed by clinical symptoms and urine analysis.2 The characteristic body odour resembling rotting fish can be intermittent, variable and influenced by diet, hormones and medications. Restriction of choline- and carnitine-rich dietary precursors (eg, fish, eggs, soybeans, peas) is difficult to maintain and effective in only 25% of patients.2 Acid soaps and body lotions can often reduce the odour.3 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.4

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.4, Psychosocial problems resulting from delayed diagnosis, body odour and the lack of cure are considerable, making this a far from “benign” disorder.

Recognition of TMAU as a significant clinical entity and increased understanding of the issues patients face are needed. Awareness of the typical patient history would facilitate prompt metabolic diagnosis and pre-empt some of the associated psychosocial sequelae. Referral of patients for genetic counselling enables short-term psychosocial support and family cascade genetic testing. Consultation with a metabolic clinic for dietary management may also be beneficial.