Mayo Clinic Laboratories > Genetics > Familial studies

Familial studies 

Helping families clarify a genetic diagnosis

When a genetic variant of interest has been identified in a patient and family members want to be evaluated for the same variation, family studies can be helpful. Used as diagnostic or predictive testing, family studies can also be useful for segregation analysis for a familial variant. In cases where variants of uncertain significance (VUS) are identified, segregation analysis assesses whether family members have the same VUS as the patient. Our targeted variant testing, which is more affordable, specific, and faster than full-gene or panel testing, is available whether or not the familial variant was detected by Mayo Clinic Laboratories.

Familial studies Test menu

Familial studies

Key testing

Frequently asked questions

How do I order Familial Variant Targeted Testing?

Targeted variant testing is available by ordering Mayo ID: FMTT/Familial Variant, Targeted Testing, and submitting the Required Patient Information paperwork.

How do I complete the Familial Variant section in the Required Patient Information paperwork?

Supply the information requested for each field. Provide the gene, the transcript (generally starts with “NM,” ex. NM_024675.4), the exon/intron number, the amino acid change (generally starts with “p.”, ex. p.Tyr1183Ter or Y1183*), the cDNA change (generally starts with “c.”, ex. c.3549C>A), and the gDNA change (generally starts with “g.”, ex. g.23614792G>T). Including a copy of the proband’s genetic test result, if available, is strongly recommended.

How is this testing priced?

CPT codes are assigned based on the gene(s) tested. For more information, see FMTT Fees & Codes in the test catalog. 

How is this testing reported?

The report will be generated in the context of the targeted variant(s) and interpreted based on the presence/absence of the variant(s) in the sample.

Can multiple variants or genes be tested?

Yes. Targeted testing may be performed for up to four variants in the same or different genes under one order.

What if I do not know the familial variant?

Documentation of the specific familial variants is required and must be provided with the specimen in order to perform this test. Review the testing algorithm or contact the molecular genetic counselor at 800-533-1710 to discuss testing recommendations.

Can testing be performed if a familial variant was previously identified at an outside laboratory?

Yes. Sending a proband sample (i.e., blood or DNA from a family member with a positive genetic test result) to be used as a positive control is strongly recommended to ensure that the specific familial variant can be detected by our laboratory. Proband samples should be sent as a separate FMTT order under the proband's identifiers (i.e., do not send the patient and proband samples under the same order number). If a positive control is not provided, the possibility of a false-negative result should be considered.

Can FMTT be performed on prenatal specimens?

Yes. For prenatal molecular testing, consultation with a laboratory genetic counselor is required at 800-533-1710. Check out our prenatal testing page for more information.

Is it possible to detect additional or incidental variants?

Yes. Analysis of regions surrounding the familial variant may be required and may result in the identification of additional sequence variants.

Is FMTT available for variant(s) of uncertain significance (VUS)?

Yes; however, this may be discouraged based on the clinical utility of the testing. To discuss, please contact the molecular genetic counselor at 800-533-1710.

Is FMTT available at no cost for VUS resolution?

FMTT may be available at no charge for family members considered to be informative for variant classification. Please contact the molecular genetic counselors at 800-533-1710 to confirm.

Is FMTT available for any gene?

Familial variant targeted testing is available for most genes that are currently part of another genetic test offered by Mayo Clinic Laboratories. Additional genes may also be available and require consultation with the laboratory prior to ordering. Genes generally not offered under this test ID currently include, but are not limited to, the following: genes with limitations related to patents; genes with limitations related to homology; mitochondrial DNA genes for heteroplasmy; and globin genes for prenatal testing. Additional genes or specific variants may be unavailable per laboratory discretion.

Why did the name change from Familial Mutation Targeted Testing to Familial Variant Targeted Testing?

The term mutation is outdated and is instead replaced by variant. In reference to a specific variant, a modifier is added to describe the level of pathogenicity, such as pathogenic variant.



Fill out the form below and one of our specialists will be in touch.