Prenatal Diagnosis for Known Familial Mutations in X-Linked Disorders

Steps and Guidelines for Submitting an X-Linked Disorder Test

For X-linked disorders, testing of a positive control is an essential aspect of accurate prenatal diagnosis. 

If the proband was diagnosed at GeneDx, subsequent prenatal diagnosis usually can be completed with a 2-week turnaround. Carrier Testing on the mother of the pregnancy is optional. During prenatal diagnosis, GeneDx must have on hand a specimen from an affected male family member and a maternal specimen for MCC testing. If such specimens were tested more than 6 months previously, fresh specimens are requested from the mother and if possible the male control.

If the proband was tested in another CLIA laboratory or a research laboratory, please follow the steps in the corresponding column below. If a Mutation Confirmation or Carrier Test (obligate carrier or accompanied by a positive control) is not ordered in advance, the 2-week TAT for prenatal diagnosis does not apply. If outside testing was done in a research laboratory, advance Mutation Confirmation is mandatory.

Previous Testing Performed By
Other CLIA Laboratory
Research Laboratory
STEPS for X-Linked Disorders
Submit the outside molecular lab results to GeneDx for review and pre-approval
Not necessary
Order Mutation Confirmation (#9001 below) on a positive relative, 1 month or more in advance.
Not necessary
Optional; otherwise send as an internal control for Step 3 or 4; no separate report
If the mother elects carrier testing, order Carrier Testing (#9011 below). A positive control specimen is required, if not already sent.
Submit a fetal specimen for prenatal diagnosis (#902 below). Specimens that must accompany the fetal specimen if not sent within 6 months are Maternal (for MCC testing) and Positive Control.
TAT will be 2 weeks in most cases
TAT will be 2 weeks in most cases, if Step 2 already complete
TAT will be 2 weeks in most cases, if Step 2 already complete


Mutation Confirmation for research results, one mutation. $350. For independent confirmation send fresh blood, 1-3 mL in EDTA, or a GeneDx buccal kit. If a fresh specimen is not available, 5 mcg stored DNA will be accepted. An individual report is provided. TAT 4 weeks. For CPT codes see the Information Sheet under Mutation Confirmation on the main web menu.
Carrier Testing for one familial mutation. $350. Specimens can be 1-3 mL EDTA blood, a GeneDx buccal kit, or 5 mcg DNA. An individual report is provided. TAT 4 weeks. For CPT codes see the Information Sheets under Carrier Test on the main web menu.
Prenatal diagnosis for one or two mutations. $2000. Includes duplicate analysis, testing for maternal cell contamination, and internal control tests. Specimens include 10 mg CVS, 10 mL AF if >15 wks, 2 confluent CV or AF culture flasks. TAT is usually 2 weeks if positive controls have been successfully tested in advance.


Click here for the test request form. Use the small box for known familial mutations on the last page of the test menu.

Click here for prenatal diagnosis CPT codes and pricing

» For specimen requirements click here to go to Amnio/CVS/Cultures under Send a Specimen