Dr Treacy brief podcast on her 2019 TMAU study

The genetic disorder journal JIMD interviewed Dr Eileen Treacy about her 2019 TMAU study.

Her paper was the most read online last year of the JIMD journal ("TMAU papers are always a popular JIMD read"). 

Treacy et al 2019 TMAU paper in JIMD 

Prof/Dr Eileen Treacy is the head of the Ireland Metabolic Unit in Dublin.

She has a long interest in TMAU, dating back 20 years or more.

Here she talks of her 2019 TMAU paper, looking at the FMO3 variants in 14 people tested positive for TMAU via the old (pre-2017) Sheffield urine test (which community thought the best world test ?). 

JIMD Podcasts · Best Of JIMD Reports

Main points of interest :

1.

Dr Treacy mentions the common variants :

E158K (possibly most people carry this at least, or on both sides ... possibly 60% of some races ?) 

selfdecode stats rs2266782

E308G (perhaps 20% Euro carry this ?, and maybe 3.5% African)

selfdecode stats rs2266780

Dr Treacy mentions that if someone carries both in-cis (from same parent), this might make them prone to mild TMAU.

2.

Although most carry some sort of FMO3 variant, Dr Treacy seems to regard most of the milds as  'carriers'.

On forums, many seem to be 'carriers', which makes one wonder if carriers are in fact 'at risk' of TMAU.

3.

Dr Treacy seems to believe TMA is the only person people with FMO3 flaws will smell of (i.e. probably not the consensus of the community).

4.

They mark TMAU cases into 3 groups :

Severe : Urine and dna test will spot pretty easily. 

Moderate : Urine test should spot some, but not all ? (community opinion)

Mild : community view is urine test will MISS most of these (now), but Dr Treacy seems to think the urine test is ok and gene test not appropriate except for severe's maybe ??

5.

She says 4% of Irish are expected to have E158K and E308G IN-CIS (i.e. from same parent).

This was expected, but maybe a surprise to hear from an expert in the context it may cause 'mild TMAU'. (maybe more so when with other variants ??).

It was anticipated estimate, as the UK FMO3 Gene test comments that 10% of UK are expected to carry these 2 variants (BUT DOES NOT MEAN FROM SAME PARENT). But if 10% carry them, then maybe 4% UK have them from same parent ??

Comment on podcast

A view is that those in forums who turn out to be currently regarded 'carriers', it seems another view to take is regard it suspicious rather than rule them out.

For instance, it might be 'TMAU' by 1000s flaws, where the person tends to have close to a 'full house' of the common variants, rather than catastrophic rare ones.

INTRONS and SILENTS : Also we don't know what destructive role non-coding parts of FMO3 might play. Mainly as no-one is interested. 

Prof John Cashman said "if someone is positive for the urine test and 'normal' in the FMO3 test, he regards it as a fault in the non-coding part'. 

So this paper is a 'halfway' paper for the community.

FMO3 gene stat paper are 'gold-dust', and tend to show the people carry combos of the common variants.

But the conclusions seem to go against us still, going with the current taught habits, and ruling the 'grays' out, rather than considering they may be mild cases.

She does mention 1 or 2 in the study were doublers for E158K (or at least says the common variant, presuming she means E158K).

Perhaps 14% Euro are in this group, and 25% African.

She calls it 'interesting'.

They seem to think  since E158K is so common (most have 1 copy at least, many are doublers), it can't cause TMAU.

But you have to look at the damage a variant is expected to cause.

It's unknown what damage E158K is expected to do, but experts seem to base it benign as its so common. 

Our community very much needs a FMO3 database, of anyone who identifies with Metabolic Malodor.

 

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