Dimethylglycine dehydrogenase enzyme (DMGDH)

dmgdhd is a disorder characterized by fish odor, muscle fatigue with increased serum creatine kinase.

Pathway: choline metabolismTrimethylaminuria is the only real 'accepted' form of metabolic body odor by those few in the medical system who are aware of any form, but another often forgotten about is dimethylglycinuria, to do with saturation of the Dimethylglycine dehydrogenase enzyme. However there seems to be only one recorded case of DMGU, and it's unclear if this is because no-one tests for it or it is so rare.
(2001 dimethylglycinuria case)

There are a lot of similarities with 'official' TMAU, in that it is thought to give off a fish smell. Also the enzyme is part of the choline metabolism. That said, presumably this enzyme deals only with one 'substrate' (it oxidizes dimethylglycine), whereas FMO3 oxidizes 1,000s of substrates (including trimethylamine). The sufferer was also said to have a high creatine kinase blood level, which may be a clue as to this problem (or maybe not). Whilst FMO3 uses riboflavin as a co-factor, DMGDH uses folate as it's co-factor.

It would be interesting to know if they discovered DMGu by using an open-ended look for volatile organic compounds in a mass spectrometer/gas chromatography test, or if they were only looking for DMG. The former would be the best starting test for defining a metabolic body odor problem, since in most cases we don't know what we are looking for yet.

Why only one case has been recorded is not known, however it would seem at the moment that an assumption could be made that DMGu is very rare and that one or more other forms of metabolic body odor are far more common.

Dimethylglycine dehydrogenase is a gene that encodes an enzyme involved in the catabolism of choline, catalyzing the oxidative demethylation of dimethylglycine to form sarcosine. The enzyme is found as a monomer in the mitochondrial matrix, and uses flavin adenine dinucleotide and folate as cofactors. Mutation in this gene causes dimethylglycine dehydrogenase deficiency, characterized by a fishlike body odor, chronic muscle fatigue, and elevated levels of the muscle form of creatine kinase in serum.

...defects in dmgdh are the cause of dmgdh deficiency (dmgdhd) [mim:605850]. dmgdhd is a disorder characterized by fish odor, muscle fatigue with increased serum creatine kinase. biochemically it is characterized by an increase of n,n- dimethylglycine (dmg) in serum and urine.

http://harvester.embl.de/harvester/Q9UI/Q9UI17.htm

Biochemically it is characterized by an increase of N,N-dimethylglycine (DMG) in serum and urine.

Pathway: Amine and polyamine degradation; betaine degradation; sarcosine from betaine...

SwissProt Accession No.: Q9UI17 Dimethylglycine dehydrogenase, mitochondrial precursor; (Homo sapiens); 99% similarity over 866 a.a.

(Last modified July 7, 2009. Version 80.)

http://www.uniprot.org/uniprot/Q9UI17&format=html