When a diagnosis of CJD has been confirmed by autopsy or in the case of a patient where an autopsy does not occur, further studies can be organised to assess whether the patient’s family is at risk of genetic CJD.
Consent by the next of kin for testing on DNA extracted from tissue after the autopsy can establish or rule out genetic CJD or other inherited forms of prion disease for that patient if/when the family require that information. Alternatively DNA from a blood sample, taken from the patient pre-mortem, can be tested immediately if there is a strong evidence of a family history of prion disease or stored until after a diagnosis of CJD is confirmed or until such time that the family require answers.
The CJDSGN advises families of the option to request a pre-mortem blood sample for DNA extraction and storage to enable options for genetic testing in the future. If an autopsy does not go ahead and there is no DNA from a blood sample stored the family has no way in the future to rule out a genetic cause for probable or possible CJD for their loved one. Family members wanting that information are then faced with individual predictive testing as opposed to testing of the DNA from the index patient that provides answers for the whole family. As 90% of cases of CJD are sporadic, families are usually keen to rule out a genetic cause and by accessing genetic services when organising testing on the index patient they are assured of appropriate support in the rare case that a genetic mutation is identified for a particular family.
The CJDSGN can assist families with information on genetic testing options and contact details of state genetic services and experienced genetic counsellors.
Predictive genetic testing for family members of a CJD patient
Genetic testing is also available to relatives who are not ill themselves but this is normally offered to people when a family member, diagnosed with CJD, is found to have genetic disease after testing or when there is a family history of two or more relatives diagnosed with CJD. Genetic counselling and testing is available at centres in each state. Family members will need a General Practitioner’s referral to their closest genetic counselling service, and they will need to book an appointment. A small amount of blood would be sampled from two separate visits to the pathology service. From these two samples, the genetic material (DNA) would be extracted and the prion protein gene can be tested.
Letter to families re genetic testing revised (pdf)