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Glioblastomas are tumors that form from astrocytes, a class of star-shaped cells in the brain that make up the glial, the separation between the nerve tissue and the pia matter (one of the three layers that cover the brain).

It is not known exactly what factors make the astrocytes turn cancerous. These tumors are usually malignant because the cells reproduce rapidly and because they are in contact with a wide network of blood vessels. Glioblastomas are generally found in the cerebral hemispheres of the brain but can also appear in any other part of the brain or in the spinal cord. It rarely spreads to other parts of the body.

There are two types of glioblastomas:

  • Primary (or de novo) glioblastoma is the most common. It starts out as a grade 4 tumor and is very aggressive.
  • Secondary glioblastoma starts as a grade 2 or 3 tumor, which grow slower. Then it becomes grade 4. About 10% of glioblastomas are this type. They tend to happen in persons age 45 or younger.

Glioblastoma represents around 17% of all primary cerebral tumors and approximately 60-75% of all astrocytomas (astrocyte cell tumors). These tumors become more frequent with age and affect more men than women. Only 3% of infantile cerebral tumors are glioblastomas.


As glioblastomas can grow very rapidly, the mlost common symptoms are generally caused by an increased pressure on the brain. These symptoms can include headaches, nauseas and vomiting, and drowsiness. Seizures, progressive cognitive dysfunction, changes in personality or behavior and memory loss are also symptoms. Depending on the location of the tumor, patients can have a variety of other symptoms such as muscle weakness and disturbances in speech and language.


Since the causes of glioblastomas are not known, there are no preventative measures.

Gene or region studied

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