Mutation-Specific Testing for Known Familial Mutations: Family Member Previously Tested at GeneDx
| Inheritance Pattern | ||||
|
STEPS when family member was previously tested at GeneDx |
Autosomal Dominant |
X-Linked |
Autosomal Recessive |
Mitochondrial (Maternal) |
| 1. Mutation-Specific Testing in both parents of proband prior to testing other family members | Recommended | Recommended | Strongly Recommended* | Not Necessary |
| 2. Using the GeneDx Sample Submission Form (Rare Disorders Requisition), select Carrier Detection in Relatives (#9011-one mutation; 9012-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.
a) Provide the name of the gene
b) Provide the name of the mutation c) Provide the GeneDx accession number or the full name of the positive relative that we previously tested. |
Required | Required | Required | Required |
| 3. Submit specimen. Our standard specimens for all 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. Gene deletion/duplication testing requires the submission of blood in EDTA.
Tissue biopsies (muscle or liver) is the preferred specimen for testing mtDNA mutations. |
TAT will be 2-3 weeks in most cases** | TAT will be 2-3 weeks in most cases** | TAT will be 2-3 weeks in most cases** | TAT will be 3-4 weeks |
*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.
***Except for Cardiology/Neurology tests where TAT is 4-5 weeks.