The issue is getting the replacement GALT (galactose one phosphate 
uridyl transferase) enzyme into each hepatocyte (liver cell) where the 
reactions that convert galactose to glucose and to UDP Galactose (a 
non-toxic useable form for tissue building allowing formation of 
glycosamino glycans, glycoproteins, glycolipids, etc) takes place. Viral 
vectors have been tried for other genetic disorders (viruses are capable 
of splicing their genes into the host DNA) but where the gene is put 
matters, and cannot be easily controlled. A liver transplant means 
lifelong anti-rejection drugs and requires a matched donor.

Without enzyme replacement, we'd still need to digest the lactose in 
human milk to glucose and galactose, and find a way to convert the 
galactose to UDP-galactose  and then put the whole bit back. Again, the 
UDP galactose still has to go to the liver so it can be further 
processed into all the useful glycoproteins and lipids. Under normal 
circumstances, most of the galactose is converted into glucose by 
another enzyme down the chain, but some stays in the UDP galactose form 
to be used in tissue building.

Again, kids with Duarte galactosemia don't need a restricted diet, they 
have some GALT activity. But because of the toxicity of galactose one 
phosphate and it's byproducts AND the relative lack of UDP galactose to 
go into building brain tissue, there are often neurological/cognitive 
problems regardless.

Wish this were all easier! Biology is so elegant and intricate and our 
understanding so primitive, when it goes wrong it's very difficult to fix.

Catherine Watson Genna BS, IBCLC  NYC  cwgenna.com


On 4/14/2012 9:24 PM, Laura Spitzfaden wrote:
> I'm wondering if there could be a supplement that a baby with galactosemia could take to break down the galactose.  I know there isn't a such thing, currently, but it seems like it should be possible.
>
> Maybe someone who has more knowledge about this could explain why there isn't such a supplement.  I am guessing that since there isn't such a thing that it is not really possible, I just don't understand why this is so.
>
> Laura Spitzfaden, LLLL IBCLC
>
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