Previously Tested at Another Diagnostic Laboratory

Family Member Previously Tested at an Outside Laboratory

Inheritance Pattern

STEPS when family member was tested at an Outside Laboratory

Autosomal Dominant


Autosomal Recessive


1. Submit the outside molecular lab results to GeneDx.
To clearly identify the mutation, please provide:For Nuclear Gene Mutations:

  1. The name of the gene
  2. The mutation in cDNA-level notation (e.g. residue c.123 G to T, where c.1 is the A of the ATG)
  3. One of the following:
    1. The mutation given at the protein level notation (e.g. Gly12Ser or G12S)
    2. The mutation given in g-DNA level notation, with reference to a specific public reference sequence
    3. A DNA sequence at least 30 bases long with the mutated base and mutation indicated

For mtDNA Mutations:

  1. The name of the gene
  2. The position in the mitogenome (m.) using reference sequence NC_012920
Required Required Required Required
2. If the individual to be tested is NOT the proband who was previously tested at the outside laboratory, provide DNA from the proband as a positive  control Strongly Recommended* Strongly Recommended* Strongly Recommended* Not necessary
3. Mutation-Specific Testing in both parents of proband prior to testing other family members Recommended Maternal carrier testing recommended Strongly Recommended** Not necessary
4. Using the GeneDx Sample Submission Form (Rare Disorders Requisition), select Carrier Detection in Relatives  (#9011-one mutation; 9012-two mutations) or Confirmation of Mutation Identified elsewhere (#9001-one mutation; 9002-two mutations) from the boxed section on the top of the second page.

For mitochondrial DNA (mtDNA) mutations, use the Neurology Test Requisition Form and select #453, #9017 or #9020 from the boxed section at the bottom of the second page.

Provide the name of the gene and information about the mutation as outlined in Step 1.

Required Required Required Required
5. Submit specimen. Our standard specimens for all sequencing tests are a single tube with 1-5 mL blood in EDTA or one pair of GeneDx buccal brushes.  DNA specimens are also accepted.  Please see our standard Specimen Requirements page.

Tissue biopsies (muscle or liver) is the preferred specimen for testing mtDNA mutations.

Gene deletion/duplication testing requires the submission of blood in EDTA.

TAT will be 2-3 weeks in most cases, unless pos control needs to be tested*** TAT will be 2-3 weeks in most cases, unless pos control needs to be tested***  TAT will be 2-3 weeks in most cases, unless pos control and/or parents need to be tested*** TAT will be 3-4 weeks

*DNA from the individual who was previously tested by the outside laboratory is strongly recommended prior to testing additional family members so that GeneDx can ensure that it is able to identify the specific mutation in the family. If a GeneDx report is desired on the previously tested individual, there will be a fee charged (Mutation-Specific Testing CPT codes and pricing). If no report is desired, please label the sample and submission form for this individual with, “POSITIVE CONTROL ONLY-No Report”
If a positive control is not provided, negative results in the Mutation-Specific test will carry a caveat stating that GeneDx did not have the opportunity to confirm that we can detect the mutation in that specific family.

** Mutation-specific testing in both parents of a child with recessive mutations is recommended to confirm that all four parental alleles can be detected prior to the testing of other family members. If the child has an apparently homozygous recessive mutation, mutation-specific testing in both parents is strongly recommended to rule out the possibility that the child has one mutated allele and one allele that is deleted or refractory to amplification. If a GeneDx report is desired on the parents, there will be a fee charged for each parent tested (Mutation-Specific Testing CPT codes and pricing). If no test report is desired for parents, testing is provided free of charge. These samples must be labeled as , “POSITIVE CONTROL ONLY-No Report” on the patient’s submission form.

***Except for Cardiology/Neurology tests where TAT is 4-5 weeks.