[Primary trimethylaminuria or fish odor syndrome. A novel mutation in the first documented case in Spain]

Trimethylaminuria or fish odor syndrome is a metabolic disorder characterized by a failure in the oxidation route from trimethylamine (TMA) to trimethylamineN-oxide (TMA-O). Primary trimethylaminuria is an inherited autosomic recessive disease due to mutations in the human FMO3 gene. High levels of free TMA in urine and other body fluids confer an unpleasant body odor resembling that of fish. Here we report a case of primary trimethylaminuria in a 4-year-old girl.

A 4-year-old girl who presented with a strong corporal scent resembling that of fish from the age of 9 months agreeing with the introduction of fish in the diet. The patient did not have other relevant personal history and had a correct psychomotor and growing development. Liver function, urea and creatinine levels were normal. The biochemical diagnosis was done by spectrometry, measuring the amount of TMA and TMA-O prior to and after fish intake.

Genetic analysis evinced that the patient was homozygous for a novel mutation in exon 3, R51G (c. 151A > G). Both parents were heterozygous.

R51G (c. 151 A > G) mutation had not been found in other patients with trimethylaminuria.