Does every member of a family with hereditary GIST have the mutation?
No, not every member of a family with hereditary GIST will inherit the familial mutation. We all typically have two copies of every gene: we inherit one copy of a gene from our mother and the other copy from our father. Similarly, if we have children, we pass on one of our two copies of a gene to each child and our partner contributes one of his/her two copies of a gene to make a complete set in a child. A person with a germ-line mutation in one of his or her c-kit or PDGFRA genes has a 50% (or 1 in 2) chance of passing on the same germ-line mutation to each of his or her children, with an equal 50% chance of passing on his or her unaltered copy of the gene. Mutations in the c-kit and PDGFRA genes can be inherited from the mother or father, and are passed on to daughters and to sons equally. Relatives who inherit the familial germ-line mutation are at increased risk to develop GIST. In addition, each of their children (or future children) would have a 1 in 2 chance of inheriting the mu
