3. Submission of blood samples from required family members
and medical documentation of prior studies: For the most
accurate interpretation of fetal test results, genetic analysis of
family members conducted in our laboratory is usually required. Review
of the pedigree and the results of any previous studies will enable
the lab and the referral source to determine which family members
should be studied to assist in the interpretation of fetal results.
Written results of diagnostic testing of the proband and/or other
key family members must be made available to the lab, either through
appropriate signed authorizations for release (if testing was performed
here) or by FAX or mail (if testing was performed elsewhere). The
samples from family members should be submitted with sufficient time
allowed to complete the laboratory analysis prior to the submission
of a fetal sample. All prenatal samples must be submitted
with a prenatal requisition
form.
Procedures for Prenatal
Biochemical and DNA Studies
The Medical Genetics Laboratories perform biochemical and DNA-based prenatal diagnostic studies for a limited number of disorders and require special handling of fetal samples. The minimum requirements for submitting prenatal cases for genetic testing in the Biochemical and DNA Diagnostic laboratories are provided below and also appear in specific sections throughout this website. The quality control measures that have been instituted in our laboratories to optimize prenatal sample processing, analysis, and interpretation are summarized below for your information.
Please be aware that our specimen requirements and quality control measures are compliant with American College of Medical Genetics (ACMG) Standards and Guidelines for Clinical Genetics Laboratories. And while these requirements are intended to provide the highest level of assurance that a single laboratory can offer, the ideal practice to assure the accuracy of prenatal diagnostic testing is through duplicate testing conducted by independent laboratories. We recommend that referring medical professionals make the necessary arrangements for these two independent analyses for their patients prior to performing the prenatal diagnostic procedure.
The minimum requirements for a prenatal study for biochemical or DNA-based genetic testing at Baylor Medical Genetics Laboratories include:
1. Prior consultation and acceptance of the prenatal case: We require that the referring center consult with our laboratory regarding prenatal cases prior to submitting any samples. Our genetic counselors are available for consultation and coordination of prenatal testing.
2. Pre and post test counseling: All
couples who are considering prenatal diagnosis should be fully informed
of the risks and benefits of prenatal testing, the accuracy and potential
limitations of the testing that is indicated for their family, as well
as the potential for adverse outcomes, including misdiagnosis, identification
of non-paternity, etc. We rely on the referring center to perform pre-test
education, to inform the couple of the special procedures for prenatal
diagnoses in our laboratory, and to communicate the results of the
studies performed in our laboratory, as indicated in our written report.
To facilitate this discussion, our genetic counselors are available
to the referring centers to answer any questions regarding our procedures.
We recommend that a copy of this summary be included in the patient’s
chart.
5. Submission of fetal specimens and repeat analyses: In order for a prenatal diagnostic study to be considered final, the following studies must be completed in our laboratory: the genetic test must be performed on two independent fetal specimens with corresponding maternal cell contamination studies. Depending upon the type of testing, the two independent fetal samples may consist of a direct amniotic fluid or CVS sample, followed by a cultured specimen, or two cultured specimens derived from independent primary clones. Please carefully note the fetal specimen requirements for specific tests (please see Biochemical Laboratory Prenatal Specimen Requirements or DNA Laboratory Prenatal Specimen Requirements). Also note that the estimated turn-around times may be test-specific. A preliminary report will be issued for the first complete set of data, followed by a final report once the confirmatory study is complete. If the referral source is providing cultured cells for analysis, we recommend that back up cells be maintained in culture until a final report is issued.
6. Billing: One standard fee is charged for prenatal tests performed by biochemical or DNA-based testing. The comprehensive charge includes testing the fetal specimens for the disorder and for possible maternal cell contamination. The charge also includes confirmation of prior parental test results for the disorder. For some disorders, this charge may also include testing of the proband. Please call the Baylor Medical Genetics Laboratories at 1-800-411-GENE (4363) if you have any more billing questions.
Please call the Baylor Medical Genetics Laboratories at 1-800-411-GENE (4363) prior to submitting any prenatal samples and coordinate with our genetic counselors regarding prenatal test requests.
Updated: 8-28-06