Cancer develops because of mutations in one or more genes. Genes hold information about how you look and how your body works, and genes are passed from parents to children. If there is an abnormality in how a gene is formed, this is called a genetic mutation.

There are two types of genetic mutations:

• Germline mutations are inherited, passed from parent to child. Between 5 and 10 percent of breast cancers are caused by germline mutations, such as those in BRCA1 and BRCA2. These mutations increase the risk of developing breast and ovarian cancer.Genetic testing for breast and ovarian cancer analyzes these two genes for mutations. The test is done on a sample of blood.

Genetic testing is recommended only for women who have:

• Multiple close family members affected with breast or ovarian cancer, particularly if the relative was diagnosed with cancer at an early age (less than 50 years old). Close family members include your mother, sister, or daughter; close family members can include men with breast cancer.
• A close family member with more than one cancer, such as breast cancer involving both breasts or breast and ovarian cancer
• Multiple generations of close family with cancer (eg, grandmother, mother, sister). Family history on the father’s side is as important as the mother’s side.

BRCA testing should be done on the relative who has cancer, whenever possible. If a mutation is not found, it is usually not helpful to test family members without cancer.

 http://www.uptodate.com/contents/patient-information-genetic-testing-for-breast-and-ovarian-cancer

What is Genetic Counselling?
Genetic counselling is available to individuals, families, or couples. It is a way to learn about genetic or hereditary disorders and the chance that they are passed on to future generations. This information helps people make decisions about their health, their pregnancies, and their children’s health.

Who will I be seeing?
You will either meet with a Genetic Counsellor or a Medical Geneticist, and sometimes both. A Genetic Counsellor is a specially trained health professional. A Medical Geneticist is a medical doctor who has special training in Genetics.

What happens at your Genetic Counselling appointment?
Medical information about you and/or your child and your family will be reviewed often using a family tree drawn up from a general family history questionnaire or, if you were referred because of a personal or family history of cancer, a cancer family history questionnaire. In some cases a physical examination may also be necessary. If an inherited disorder is found, you will then be given the medical facts of the disorder, and its symptoms, and how it is passed on in families.

What do I bring?
If asked, you should bring family photos and previous medical reports.

Will I be tested?
Not every patient who comes for genetic counselling is tested. During your appointment, the Geneticist or Genetic Counsellor will talk with you about various testing options available to you and your family. Most testing is done on a blood sample.

Do I have to pay for anything?
Genetic Counselling and testing is usually covered by your provincial health care insurance. Exceptions may occur and will be dealt with on a case-by-case basis. Always bring you/your child’s health cards.

How long will I be there?
Appointments usually take about one hour. This gives you plenty of time to ask the doctor or genetic counsellor questions. Please try to arrive 10 minutes before your appointment so that registration can be completed first.

http://www.cheo.on.ca/en/geneticcounselling?mid=ctl00_LeftMenu_ctl00_TheMenu-menuItem004