Explaining genetic terms and concepts
| Genetic term . | Definition . |
|---|---|
| Germ line genetic change | A genetic change that is present in all (or almost all) of the cells in a person’s body. This change may be present in a parent, siblings, and other relatives and can be passed on to children. When a patient’s cancer or tumor is treated, the genetic change will continue to be present. |
| Somatic genetic change | A genetic change that is only present in a cancer or tumor. This type of change is not present in other family members and cannot be passed on to future generations. When the cancer or tumor is treated, the genetic change will disappear. |
| De novo genetic change | A genetic change that is new in the patient, meaning that neither parent has it. The patient can pass the genetic change on to the future generations. |
| Diagnostic testing | Testing to understand the cause of a patient’s disease phenotype. The results might change the patient’s treatment and long-term care.∗ |
| Predictive testing | Testing in healthy individuals to understand the risks for disease. This is the type of testing that is often done for BM donors. Generally, even if the genetic risk is present it does not mean the patient will definitively develop the disease, but it can indicate a higher risk than other people of the same age. Understanding risks can affect surveillance and screening.∗ |
| Segregation testing | Testing family members for a variant that was identified in a patient to determine whether it was inherited or de novo. This will determine whether the variant is present in other family members. If the variant is present in family members who have a phenotype similar or related to the one in the patient, this information can clarify the potential pathogenicity of a VUS. |
| Genetic term . | Definition . |
|---|---|
| Germ line genetic change | A genetic change that is present in all (or almost all) of the cells in a person’s body. This change may be present in a parent, siblings, and other relatives and can be passed on to children. When a patient’s cancer or tumor is treated, the genetic change will continue to be present. |
| Somatic genetic change | A genetic change that is only present in a cancer or tumor. This type of change is not present in other family members and cannot be passed on to future generations. When the cancer or tumor is treated, the genetic change will disappear. |
| De novo genetic change | A genetic change that is new in the patient, meaning that neither parent has it. The patient can pass the genetic change on to the future generations. |
| Diagnostic testing | Testing to understand the cause of a patient’s disease phenotype. The results might change the patient’s treatment and long-term care.∗ |
| Predictive testing | Testing in healthy individuals to understand the risks for disease. This is the type of testing that is often done for BM donors. Generally, even if the genetic risk is present it does not mean the patient will definitively develop the disease, but it can indicate a higher risk than other people of the same age. Understanding risks can affect surveillance and screening.∗ |
| Segregation testing | Testing family members for a variant that was identified in a patient to determine whether it was inherited or de novo. This will determine whether the variant is present in other family members. If the variant is present in family members who have a phenotype similar or related to the one in the patient, this information can clarify the potential pathogenicity of a VUS. |
For predictive and diagnostic testing, care should be taken when discussing the potential benefits. If there are no standardized surveillance or treatment options available and no way to improve morbidity and mortality, this information should be discussed with the patient to aide in decision-making regarding germ line testing. Some patients may only be interested in testing that has clear implications for their health care.