If you have a mutation of any of the SDH subunits (a,b,c, or d), the next important question to ask is whether or not it is a germline mutation. (So far, data has indicated that 80% of SDH-deficient tumors are germline). The term "germline" means that the mutation is present in every cell of your body. Germline mutations are hereditary, and can be passed on to your children. For this reason, genetic testing and counseling could be informative for parents, siblings and other family members. If a family member tests positive for the mutation, this does not mean that they will get GIST.