THE FISH ODOR SYNDROME - BIOCHEMICAL, FAMILIAL, AND CLINICAL ASPECTS

Objectives-To study the biochemical, familial, and clinical features o f the fish odour among subjects with suspected body malodour. Design-S ubjects who responded to a newspaper article were screened for the fis h odour syndrome by interview and biochemical tests. Families of subje cts with the syndrome were tested if possible. Setting-St Mary's Hospi tal, London, and some interviews at subjects' homes. Subjects-187 subj ects (28 males) with suspected body malodour, of whom 156 (19 males) u nderwent 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 collect ed over 24 hours under normal dietary conditions and for eight hours a fter oral challenge with 600 mg trimethylamine. Results-The fish odour syndrome was diagnosed in 11 subjects: the percentage of total trimet hylamine excreted in their urine samples that was oxidised to trimethy lamine N-oxide was <55% under normal dietary conditions and <25% after oral challenge with trimethylamine (in normal subjects >80% of trimet hylamine was N-oxidised). Parents of six of the subjects with the synd rome were tested: all showed impaired N-oxidation of excreted trimethy lamine (< 80%) after oral challenge, indicating that they were heteroz ygous carriers of the allele for the syndrome. The syndrome was associ ated 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 fa ctor in patients complaining of body malodour.