Huntingtons Disease

Sorry to hear aout your GF diagnosis.

I do not really know why the doctor told that to your girlfriend. As you may have read already it is an autosomal dominant disease, it means that is inevitable if you have one single copy of the gene (genes always work in teams mostly pairs, many diseases never express if an individual has at least one healthy copy of the gene, but in this case this does not applies).

If she already tested positive to the gene on her cells she will develop the disease. But if she has not been tested she has 50 percent chances to develop the disease.

Other common characteristic of Hungtington in something reallynasty callen genetic anticipation. It means she may develop it at a younger age than her mother. Maybe that was what the doctor was meaning that she won´t start to be sick soon.

You can always seek for a second opinion. Have another lab run the confirmatory test. If she test positive in two different labs then there is no doubt. Also a genetic councelur would be usefull. They are specialist that help guiding people with genetic diseases through their lives about what to expect and how to react against this troublesome diseases.