About Genetic Services
Ordering Genetic Testing
Genetic tests may be ordered by a medical geneticist or
genetic counselor as part of a genetic consultation, or
they may be ordered by a primary or specialty care
provider. Considerations when ordering a genetic test
Choosing a Laboratory
GeneTests was created to simplify the search for
genetic testing laboratories, which may be difficult to
locate. For many diseases, there may be only one laboratory
providing genetic testing. U.S. patents have been issued
covering diagnostic testing for some genetic disorders. A
given laboratory may or may not be the exclusive licensee
to such a patent. If there is a choice of laboratories, the
following factors should be considered:
laboratory personnel have two major roles: processing
patient samples (technologists), and interfacing with
referring clinicians regarding their patients (clinical
consultants). Lab personnel, who are usually certified in
their specialty, may include lab directors, supervisors,
technologists, and genetic counselors.
Compatibility: The test offered by the laboratory
must match the specific clinical need
testing gives a result which can be used in patient
testing usually does not. If only research testing is
available, the patient or family may choose to defer
testing until a clinical test is available.
- The test methodology must be suited to the testing
purpose (e.g., Prader-Willi syndrome can be
diagnosed with methylation testing, but other tests are
required for recurrence risk counseling).
- Some diseases are caused by mutations in more than
one gene. It is important to be sure that the lab
selected is testing the appropriate gene(s).
- Different kinds of DNA tests are available. The
laboratory selected should offer what is most appropriate
for a specific clinical situation. For instance:
- A specific gene mutation (e.g., if the
familial mutation has been identified)
- A panel of mutations (e.g., the Ashkenazi
Jewish BRCA1 panel of 3 mutations)
- The complete gene sequence
Reliability: Direct contact with the laboratory is
needed to assess the laboratory's experience and
- Does the laboratory have any other certification?
(Laboratories with clinical listings in GeneTests
- Is the laboratory associated with a reputable company
- Is the laboratory director board-certified?
- Is the laboratory's work published in the medical
- What is the laboratory's experience with the specific
test being ordered?
Ease of Communication
- What professionals are on staff to help assess the
appropriateness of testing, determine the best testing
paradigm for the family, and interpret test results?
- Does the laboratory have information on tests offered
and logistics of sample collection and shipping easily
available by phone, fax, or Internet?
- What information is contained in the test result
report (e.g., raw data, interpretation,
references, sensitivity and specificity
- Some states have restrictions on insurance coverage
or, as is the case in New York, additional regulatory
- Samples shipped outside of the U.S. must go through
Customs, which requires that hazard identification and a
statement of value accompany the sample. Language
barriers and time zones can also be an issue.
Turn-Around Time: Time from sample receipt to test
result report may vary
- Clinical laboratories generally have similar
turn-around times for tests performed using the same
- A shorter turn-around time is advantageous only when
it can be determined that quality control and
thoroughness are not compromised.
- Test results for pregnancy management (prenatal
diagnosis) are considered urgent due to restrictions on
options late in pregnancy. Pregnancy dating should be
included with all prenatal samples.
- The laboratory should be notified in advance of any
sample that is "stat" (rush), as the sample processing
may be different.
Cost: May vary from less than $100 to more than $2000
based on several factors
- Test methodology. Low complexity tests (e.g.,
single gene mutation) are less expensive than high
complexity tests (e.g., full gene sequencing)
- Laboratory testing strategy. Some labs test for a
large number of mutations all at once; other labs test in
stepwise fashion, beginning with the most common
- Number of individuals tested. Several family members
may need to be tested to obtain a meaningful test
- Contractural agreements. Hospitals, insurers, and
laboratories negotiate contracts to set the price of
testing and amount of reimbursement.
- Specimen handling. Some cell types require culturing
or other special handling before testing.
- Additional services. Genetic consultation or
counseling is usually recommended and sometimes required
before genetic testing is performed. These fees should be
considered in the total cost.
Pretest Counseling and Informed Consent
If genetic testing is clinically available and useful
for a particular patient, the patient needs to understand
why it is being offered and its implications for medical
management and psychosocial well-being. If a competent
patient (or parent/guardian) agrees to the proposed genetic
test after full disclosure, this constitutes informed
consent. Informed consent may be verbal or written. Some
laboratories require written documentation of informed
consent. (See sample informed consent form from CompGene.)
Pretest counseling includes:
Additional issues relevant in some testing
- Need to clarify biological relationships (parentage,
zygosity) for linkage studies.
- Potential discrimination in employment, insurability
or educational opportunities, especially in predictive
testing. (Some states have State Genetics
Laws in place prohibiting genetic
- Results from research testing are not generally
available for patient care.
Sample Logistics and Supporting Documentation
Contact the lab directly to ask the following
What are the sample requirements?
- Are samples from other family members needed?
- What specimen
type is needed?
- Does the specimen need to be cultured before
- What is the requested amount of specimen? Will less
be accepted in hard-to-draw situations?
- What information should be included on the
What supporting documentation is needed?
- Does the lab have a specific requisition form?
- What clinical history should be included?
- Are medical records or test results on family members
- Is family history needed for test interpretation? A
pedigree is an efficient way to show family
relationships. See Sample
Pedigree for Laboratory Documentation (pdf).
- Is ethnicity relevant to test interpretation?
- If crossing international borders, are hazard labels
and customs paperwork included?
How should the sample be transported?
- What is the correct delivery address?
- When is delivery accepted?
- Should the sample be frozen, refrigerated or at room
temperature during shipping?
- Is there a courier to the lab, or is taxicab, mail or
overnight shipping required?
Test Result Interpretation and Follow-Up
Test results are provided in writing by the laboratory
to the referring clinician. The details of the lab report
vary by lab, but may include:
- Raw data
- Clinical interpretation of test result
- Sensitivity and specificity information
See Sample Lab Report.
The clinician explains the meaning of the test result to
the patient and to other family members as needed. Test
results and follow-up should be documented in the medical
record and a copy made available to the patient. For many
conditions, educational materials may be available from
patient support organizations.
Parent support & information:
For Positive Test Results
If the test purpose was...
The interpretation is...
And follow-up includes genetic
Clinical diagnosis is confirmed
Medical management and treatment
The likelihood of showing disease symptoms
Counseling for life planning;
Medical management if available
The patient is a carrier
Testing offered to partner;
Prenatal testing offered if indicated
A fetus is diagnosed with a specific
Pregnancy treatment/management or
Disease in a newborn is suggested;
Carrier status in a newborn may be
Confirmatory testing; if positive, medical
management and treatment
Carrier testing offered to parents
1. Genetic Counseling includes
discussion of expected course of the disorder;
possible interventions; underlying cause; risks to
family members; reproductive options; support.
For Negative Test Results
If the test purpose was...
The interpretation is...
And follow-up may include...
Clinical symptoms are unexplained
Further testing and/or follow-up genetic
The likelihood of showing symptoms is
Counseling for survivor guilt and long-range life
No high-risk surveillance needed
High likelihood that the individual is not a
Low risk of having a child affected with the
condition in question
Testing offered to other family members if
If fetus was symptomatic (e.g., by
ultrasound findings), clinical symptoms remain
unexplained and may need further investigation.
If fetus was not symptomatic, the chance of the
condition tested for is very small.
If fetus was symptomatic, further testing and/or
If fetus was not symptomatic, no follow-up
The newborn is not expected to have the condition