Carrier Screening in Canada
Reproductive Genetic Carrier Screening in Canada
Canadian guidelines for maternity care and reproductive healthcare providers on pre- and post-conceptional reproductive carrier screening were updated in September 2016 by the Society of Obstetricians and Gynaecologists of Canada (SOGC) Genetics Committee and the Canadian College of Medical Geneticists (CCMG) Clinical Practice Committee.
The first step of genetic screening is obtaining a three-generation family history of both the woman and the biological father of the future or current pregnancy. Family health history-based risk assessment is still the gold standard in initial assessment for heritable conditions.
For condition and ethnicity specific guidelines for reproductive carrier screening, see the point of care tools below. Each tool contains summary information for taking a pre-conception family history to identify red flags which should prompt a referral for genetic consultation followed by specific information on screening for a specific disorder or group of disorders.
Point of care tools to download:
- Ashkenazi Jewish (AJ) reproductive genetic carrier screening. See HERE for how genetic testing is offered in your province.
- French Canadian reproductive genetic carrier screening
- Reproductive carrier genetic screening for hemoglobinopathies
- Reproductive carrier genetic screening for specific disorders(cystic fibrosis (CF), fragile X syndrome and FMR1-related disorders, spinal muscular atrophy(SMA))
All couples planning their families should have a three-generation family history taken, ideally in the preconception period. Attention should be paid to the red flags below to assess risk to future offspring.
A personal or family history of:
congenital anomaly e.g. congenital heart defect, neural tube defect
intellectual disability or developmental delay
genetic syndrome e.g. neurofibromatosis, Noonan syndrome
chromosomal disorder e.g. Down syndrome (trisomy 21), familial translocation
muscular disorder e.g. X-linked Duchenne and Becker muscular dystrophies
bleeding disorder e.g. X-linked hemophilia A or B
stillbirth
sudden unexplained death
other major health concerns such as cardiomyopathy, neurological disease, epilepsy, hearing loss, autism, and psychiatric disorders
A history of any of these red flags should prompt referral for genetic consultation. Individuals and their partners should be encouraged to make their best efforts to obtain confirmatory information such as medical records, genetic test results, even family photos.
One’s ethnicity is an important piece of risk assessment as some populations are known to have a higher incidence of certain genetic conditions due to a founder effect. Founder effect confers reduced genetic diversity in a population descended from a small number of ancestors. Founder mutations refer to specific gene mutations observed at high frequency in a specific population due to the presence of that gene mutation in a single or small number of ancestors.
Other considerations:
- There is a higher incidence of hemoglobinopathies in certain populations, screening recommendations are here
- Canadian recommendation for reproductive carrier screening in individuals of Ashkenazi Jewish ethnicity are here, and those from certain regions of Quebec are here
- Canadian carrier screening recommendations for cystic fibrosis, fragile X syndrome and spinal muscular atrophy are here
- Individuals who are of Cree ancestry have a higher carrier frequency of Cree encephalitis (1/30-1/17) and Cree Leukoencephalopathy (~1/10). Screening programs have been developed in some regions or communities. The CE-CLE Screening Program is offered to adults in the Awash clinics and to high school students
- Aboriginal Manitoba populations have a higher incidence of cerebro-oculo-facio-skeletal syndrome
- Newfoundland populations have a higher incidence of Bardet Biedl syndrome and neuronal ceroid lipofuscinosis
- A maternal family history of bleeding disorders in a woman’s male relatives (father, brother, and/or maternal uncles) should prompt referral for consideration of carrier screening of X-linked hemophilia.
- Families with Amish, Mennonite, or Hutterite background based on family history and/or geographic or religious settlement locality, in addition to a three-generation family history, should be offered referral for genetic consultation. For an online North American Database containing information about disorders more common in these populations (e.g. references, founder mutations, condition, clinical presentation), please see the Amish, Mennonite, and Hutterite Genetic Disorders Database website.
Expanded carrier testing is privately available genetic testing which screens an individual for more than just family history or guideline/ethnicity-based conditions. See our *new* pre- and post-test Point of Care tools here and the Education Module for more information on this type of testing.
Ashkenazi Jewish reproductive carrier genetic screening in Canada.
| Province or Territory | How to order testing | Conditions screened for |
|---|---|---|
| Alberta | Testing is not available in-province Approval for out of province funding must first be obtained through the Genetic Resource Centre. Applications are reviewed on a case-by-case basis Your local genetics clinic | o Tay-Sachs disease o Canavan disease o Familial dysautonomia |
| British Columbia and Yukon | Instructions, requisitions and counselling information found here Your local genetics clinic Molecular Genetics Laboratory at BC Children’s and BC Women’s Hospitals | o Tay-Sachs disease o Canavan disease o Familial dysautonomia o Fanconi anemia type C |
| Manitoba | Requisition is available here through the Diagnostic Services of Manitoba Your local genetics clinic Diagnostic Services of Manitoba | o Tay-Sachs disease o Canavan disease o Familial dysautonomia o Fanconi anemia group C |
| Maritimes (New Brunswick, Nova Scotia & Prince Edward Island) | Contact your local genetics clinic | o Tay-Sachs disease o Canavan disease o Familial dysautonomia o Fanconi anemia type C |
| Newfoundland & Labrador | Must be ordered by a geneticist Your local genetics clinic | |
| Ontario | Hospital for Sick Kids Genome Diagnostics Requisition here Your local genetics clinic Hospital for Sick Kids information sheet Hospital for Sick Kids Genome Diagnostics Laboratory Test Catalogue | o Tay-Sachs disease o Canavan disease o Familial dysautonomia o Bloom syndrome o Fanconi anemia group C o Mucolipidosis IV o Niemann-Pick disease |
| Quebec | McGill University Health Centre Molecular Genetics Test List & Sample requirements and Requisitions Your local genetics clinic McGill University Health Centre Molecular Genetics | o Tay-Sachs disease o Canavan disease o Familial dysautonomia |
| Saskatchewan | Refer to Genetics Your local genetics clinic Saskatoon Health Region Medical Genetics | o Tay-Sachs disease o Canavan disease o Familial dysautonomia o Fanconi anemia group C |