What is trimethylaminuria?

Trimethylaminuria is a rare disorder characterised by impaired metabolism of trimethylamine, a volatile amine which has a strong odour resembling rotting fish. Trimethylamine leaves the body as a gas through the breath, sweat and other bodily secretions, giving individuals an unpleasant and distinctive body odour. There are both acquired and inherited forms of the condition which arise from disturbance of a metabolic axis including the gut microbiome and a hepatic enzyme FMO3.

Why did we do this study?

Individuals with trimethylaminuria often appear physically healthy. However, we now understand the disorder in its biopsychosocial context and know that social isolation and stress eventually impact negatively on physical health. Until now there has been only anecdotal and small study evidence of the psychological and social consequences of living with trimethylaminuria. It is estimated that 1 in 40,000 people may have the inherited form of the disorder, with many more having a mixed or acquired version of the disorder. There is currently no guidance on the diagnosis and management of trimethylaminuria in the UK.

What did we find?

Our findings show that trimethylaminuria can cause immense hardship and distress. Quantitative data showed that 90% of respondents felt disadvantaged in the workplace, and 90% felt disadvantaged in their social lives. Interestingly, only 28% and 21% of respondents felt disadvantaged in school or university respectively. 90% of respondents had suffered bullying, harassment, and ostracism in the workplace. Another key theme which emerged was difficulty and delay in gaining a diagnosis or diagnostic test. Only 73% of respondents had been offered a diagnostic urine test for trimethylaminuria, and only 22% had been offered a genetic test. Qualitative responses highlighted a concerning lack of understanding and compassion from clinicians, and that people with trimethylaminuria generally felt unsupported by the health service.

What next?

Respondents had an opportunity to suggest changes which would improve quality of life. Many suggested that a greater understanding of trimethylaminuria and its consequences by their healthcare providers, authority figures and the public. Respondents wished that there were protections in place to stop them from being discriminated against, others thought that because of the unpredictable nature of symptoms more flexibility in work and study would be beneficial. These suggestions could be facilitated by classifying trimethylaminuria as a disability under the Equality Act 2010. This would protect individuals from discrimination and allow reasonable adjustments by employers and educators.

There are currently no definitive treatments for trimethylaminuria, but trimethylamine excretion can sometimes be lessened with a restrictive diet, riboflavin supplements, and probiotics. Short-term antibiotic therapy has been used in some individuals, however this does not cause long-term symptom relief. Importantly, there is no clinical guidance for the management of trimethylaminuria. Publication of such evidence-based advice would be hugely beneficial for clinicians and patients alike.