Information on the SUOX gene test?

[Guest guest]

I am looking for any study regarding the sulfite oxidase (SUOX)

enzyme polymorphism S370S that some people here have been tested for

(as part of the Yasko tests). The S370S SNP was discovered in a

2002 case study on a newborn child with a SUOX deficiency. S370S is

mentioned as an aside in that study, as the real cause of the

deficiency was a severe mutation. The child eventually died due to

that mutation. However, interestingly, even though the parents were

both heterozygous carriers of that mutation, such that " sulfite

oxidase activity in protein encoded by the affected allele " was

completely abolished, the parents still displayed " no clinical

symptoms. "

The reason for this finding, is actually not too surprising. This

is due to the fact that a person's sulfite oxidizing capacity, is

far greater than the amount of sulfite one is normally exposed to.

To quote a 1988 article on SUOX:

" From measurements of sulfite oxidase activity and autopsy samples

of human liver it has been estimated that the total sulfite

oxidizing capacity of the adult liver is 4000 to 8000 mmol/day,

compared to the average endogenous production of 25 mmol/day and a

maximum exogenous intake of 2.5 mmol/day. "

A reduction of the activity of an enzyme doesn't necessarily lead to

a reduction of the enzmatic process. For certain processes, the

quantity of an enzyme is able to make up for a reduction of the

quality of the enzyme. This is most likely the case for SUOX.

I've not found any study which shows that a common SUOX polymorphism

results in lower SUOX activity, as measured by specific tests for a

SUOX deficiency, such as elevated urinary S-sulfocysteine. If

anyone knows of such studies, please email me. Thanks! - Mark