1993 Mitchell TMAU paper : The fish odour syndrome: biochemical, familial, and clinical aspects

This is an interesting TMAU paper from 1993 by a TMAU expert mostly involved in studies that looked at biochemical aspect of TMAU amongst body odor sufferers, Dr Stephen Mitchell of London. Unfortunately he no longer seems to do such research.

Not much seems to have changed since 1993, apart from now they have a test for the genotype testing (DNA test), and also perhaps the 'reference range' in the urine test has come down to a lower level ? In this paper, most of the TMAU cases are regarded positive if their result was around 50% or less. Perhaps today, the borderline is set at around 85% ? The paper seems to have come about due to an article in a UK newspaper in 1991. It resulted in 187 body odor sufferers writing to Dr Mitchell, who then did a survey of them, including a TMAU urine test for 156 of them. Of the 156, 11 were regarded as obvious TMAU cases (using the reference range of the time).

Of the 11 TMAU cases, 6 of them had their parents do the TMAU 'carrier' test (taking 600mg of TMA), which they all 'failed'. Another interesting point is that the 11 cases has TMA levels in the 100's, which seems on the high side.

The fish odour syndrome: biochemical, familial, and clinical aspects.
Ayesh R, Mitchell SC, Zhang A, Smith RL.

Department of Pharmacology and Toxicology, St Mary's Hospital Medical School, (Imperial College), London.
Comment in:

BMJ. 1993 Oct 16;307(6910):1009.
BMJ. 1993 Sep 11;307(6905):639-40.
Abstract
OBJECTIVES: To study the biochemical, familial, and clinical features of the fish odour syndrome among subjects with suspected body malodour.

DESIGN: Subjects who responded to a newspaper article were screened for the fish odour syndrome by interview and biochemical tests. Families of subjects with the syndrome were tested if possible.

SETTING: St Mary's Hospital, London, and some interviews at subjects' homes.

SUBJECTS: 187 subjects (28 males) with suspected body malodour, of whom 156 (19 males) underwent biochemical tests. Five families of six of the subjects with the fish odour syndrome agreed to further tests.

MAIN OUTCOME MEASURES: Amounts of trimethylamine and trimethylamine N-oxide in urine collected over 24 hours under normal dietary conditions and for eight hours after oral challenge with 600 mg trimethylamine.

RESULTS: The fish odour syndrome was diagnosed in 11 subjects: the percentage of total trimethylamine excreted in their urine samples that was oxidised to trimethylamine N-oxide was < 55% under normal dietary conditions and < 25% after oral challenge with trimethylamine (in normal subjects > 80% of trimethylamine was N-oxidised). Parents of six of the subjects with the syndrome were tested: all showed impaired N-oxidation of excreted trimethylamine (< 80%) after oral challenge, indicating that they were heterozygous carriers of the allele for the syndrome. The syndrome was associated with various psychosocial reactions including clinical depression. CONCLUSIONS: The fish odour syndrome can be inherited in an autosomal recessive fashion. It should be considered as a possible causative factor in patients complaining of body malodour. 

Full paper : The fish odour syndrome: biochemical, familial, and clinical aspects