Genetics Laboratory Frequently Asked Questions

Refer to the testing services available to search for a particular test requested. Please contact the laboratory if you are still unsure of what sample type/volumes are acceptable.

Refer to the sample requirements and shipping to search for a particular sample type. Please contact the laboratory if you are still unsure of what sample type is acceptable.

All fresh tissue types (e.g., kidney, skin, liver) are accepted. Tissues which have been formalin-fixed and embedded in paraffin (FFPE) are not accepted.

Products of Conception (POCs), and specimens from intrauterine fetal deaths (IUFDs) and stillbirths must be sent to a Pathology Laboratory, where they will be prepared and then transferred to the Genetics Diagnostic Laboratory for testing if sample fits criteria for testing. Completed requisitions for both the Pathology and Genetics Diagnostic Laboratories are required.

Please note that cytogenetic testing of POCs, IUFDs and stillbirths is a restricted service; POC and IUFD samples for referred for recurrent pregnancy losses will not the accepted, unless there are documented ultrasound findings or congenital malformations.

Please contact the laboratory if you are still unsure if the sample type or clinical indication is acceptable.

Refer to the benchmark turn-around-times (TAT) for all tests. These are located under each test in our Genetics tests available page.

For inquiries about pricing for tests ordered outside of Ontario, please contact our laboratory for a price list.

Due to laboratory licensing and insurance regulations, we are unable to accept samples for genetic testing from outside of Canada.

Visit the Genetic Testing Registry (GTR) to search for a desired test. The GTR provides a central location for voluntary submission of genetic test information by providers.

Molecular

Prenatal testing is available for most molecular genetics tests listed, with the exception of facioscapulohumeral muscular dystrophy (FSHD), hereditary breast cancer, hemochromatosis and thrombophilia.

Cytogenetic

Prenatal testing is available for most cytogenetic tests, including chromosome analysis, Rapid Aneuploidy Detection (RAD) and metaphase FISH testing. However, genomic microarray analysis and follow up qPCR testing for CNVs detected by genomic microarray analysis are not available for prenatal samples.

• Prenatal (amniotic fluid, CVS or cord blood) samples
• Infant less than or equal to 3 months old
• Pregnancy: when patient or patient's partner is pregnant
• Parents of an "in utero" fetus with an abnormal karyotype
• New leukemia diagnoses: AML, ALL and CML
• New or suspected diagnosis or solid tumor or Burkitt/high-grade lymphoma

Please contact the laboratory if you would like a case to be prioritized for any other reason.

DNA will be accepted for all molecular tests except FSHD and SMA; note peripheral blood samples older than 3 days will not be accepted for FSHD testing. Refer to testing services available for a complete list of DNA requirements.

Please provide both patient samples for a couple who have had:

• A previous pregnancy with structural chromosome abnormality or unusual variant
• Infertility or unknown etiology
• >3 pregnancy losses with the same partner

Please reference the partner's name and date of birth on both requisitions.

The Genetics Diagnostic Laboratory at CHEO will provide molecular and cytogenetic analysis for a select test menu of disorders affecting children and adults.

In contrast, the Genetics Clinic at CHEO offers assessment, counselling and possible follow-up for your patients. The clinic accepts referrals from physicians and other health care providers.

No. The CHEO Genetics Diagnostic Laboratory does NOT accept buccal swabs or saliva samples for any of our testing services. Please refer to the Sample requirements and shipping page for accepted sample types. 

If the proband was initially tested by the CHEO Genetics Diagnostic Laboratory

Please indicate on the requisition the variant(s) for which familial testing is required and the proband's identifiers (first name, surname, DOB and CHEO pedigree number).

If the proband was initially tested by another laboratory

Please provide a copy of the proband's genetic testing report. Information including the gene, transcript (NM#), c. and p. nomenclature as well as classification are required to ensure testing for the correct variant. Contact the laboratory to discuss a specific case/scenario if a copy of a family member's genetic testing report is not available.

Positive control samples are accepted, but not required in the majority of cases. Please contact the laboratory to see if a positive control is required for your specific case/scenario.

Visit the Ontario Genetic Test Directory( OGTD) to search for a desired test. This directory lists diagnostic genetic tests available in Ontario for rare and inherited diseases, including molecular genetic, constitutional cytogenetic and pharmacogenetic tests.

The CHEO Genetics Diagnostic Laboratory will provide re-interpretation if the following criteria are met:

• Your patient is found to carry the familial variant
• The variant was previously interpreted by CHEO Genetics Diagnostic Laboratory

AND

• The previous interpretation of the variant was provided by CHEO > 12 months ago OR we have become aware of a significant change in the information used to interpret the variant (e.g. a relevant functional study has been newly published or was not included in the initial interpretation)

Please note: in most cases, the detection of a variant in one additional affected family member would not be sufficient evidence to change the classification of that variant.

If your patient is found to carry the familial variant, but the familial variant does NOT meet the criteria for re-interpretation, then the initial interpretation will be provided on the family member’s genetic testing report.

For variants previously identified by an external laboratory:

CHEO will not provide an updated interpretation. Please contact the external laboratory to request variant re-interpretation.

Providers can also review relevant resources to check for updated evidence that may impact a variant’s classification, including:

• Relevant literature
• ClinVar
• GnomAD

Please feel free to email GeneticsLabCounsellors@cheo.on.ca if you have additional questions.

Yes, single gene(s) can be requested, as long as these genes were originally offered on a panel. Please select on the requisition “Single Gene Testing” under “Test Requested” and specify the gene(s) you would like tested.