What is G-6-S?
G-6-S is a genetic deficiency. There are 3 statuses - normal, carrier, and affected.
A 'normal' goat does not have any genetic mutation. A 'carrier' has one recessive gene that carries the mutation but will never have any symptoms. An 'affected' goat has two mutations and will be symptomatic.
As far as I am aware, in the goat world this Deficiency has only been found in Nubians and Nubians crosses. The human version of this deficiency is called Sanfillippo Syndrome. There are 4 types which can affect humans but goats are only know to have one (Type D). It is similar to Amylopectinosis which is found in Quarter horses.
There is only one type of deficiency found in an affected goat, Type D. This type is a mutation of the gene lacking the ability to produce N-acetylglucosamine 6-sulfatase, which is the enzyme necessary to break down complex sugar molecules. Heparen sulfate is a complex sugar molecule and is found in each cell wall. In an affected goat, this heparen sulfate builds until the cells cannot do what they are supposed to do.
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Why is it important?
This is a bit of a loaded question..... some breeders feel all carriers and affected should be culled and others feel it is not important due to it's self-limiting factor.
I am on the fence... =)
A carrier is perfectly fine as an individual. It will live a normal life.
The issue comes when animals aren't tested and a carrier is bred to a carrier. There is a chance that 50% of their offspring will be affected. The affected kids will not thrive and will have a shortened life-span..... in that sense it is self-limiting.
A lot of this boils down to prevention and good management. I do not consider a carrier a cull but a breeder must be knowledgeable about the deficiency and not breed two carriers.
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How would a carrier affect my herd?
Another loaded question....! It depends how you breed. Do you test *all* your goats? If not, you could be in for some heartbreak.
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How can I test my goats?
UC Davis
TVMDL
MAXXAM
Please note, these tests are not 100% accurate so if you test one generation and never test again, the chance of error increases. It is recommended by one lab that breeders test every few generations.
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Other thoughts....
General genetics would reason that there are degrees of traits and that one trait is affected by multiple alleles. Anecdotally, nothing has been researched. Unfortunately there is not enough interest or funding to do research into which traits are connected.
There is also no mitochondrial testing available at this time that I am aware of.
There have been more that a few people who have traced their lineage back to a certain carrier goat and that goat produced very "milky" daughters. The theory by those people is that in line breeding for certain traits we have lost others and increased the probability of G-6-S.
There is no known way of boosting the system to prevent carriers or affected goats although I do have some theories. =D
Enzymes will not cross the placenta and won't change the functionality of the embryo.
The pancreas is where most of the enzymes for breaking down sugars are produced.
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Helpful Links
http://vdi.sagepub.com/content/10/2/181.full.pdf
http://www.goatworld.com/articles/g6s.shtml
http://www.hobbyfarms.com/.../test-nubian-goats-for-g65...
http://tvmdl.tamu.edu/.../30/faqs-on-g6s-diagnostic-testing/
http://vdi.sagepub.com/content/22/4/622.full
The Truth: Every Living Thing is a Genetic Defect Carrier
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If you are on Facebook there are several groups with info also.
Feel free to contact us with any questions or if you find other info that might be interesting.