Short answer
FH genetic testing looks for inherited pathogenic or likely pathogenic variants in the fumarate hydratase gene. These variants can cause FH tumor predisposition syndrome, also called hereditary leiomyomatosis and renal cell cancer, or HLRCC. The result matters most when the personal or family pattern includes cutaneous leiomyomas, early or multiple uterine fibroids, FH-deficient or aggressive kidney cancer, or relatives with a known FH variant. A tumor-only FH finding is not automatically inherited, and an FH VUS should not be treated like a confirmed harmful variant.
How to read the result
| Report wording | Practical meaning | What to ask next |
|---|---|---|
| Pathogenic or likely pathogenic germline FH variant | The lab found an inherited FH change with enough evidence to guide syndrome-level counseling. | Which kidney surveillance, dermatology, gynecology, and family-testing conversations apply to this exact result? |
| FH variant of uncertain significance | The lab found an FH change, but its health meaning is not established. | Should care be based on personal and family history while the variant remains uncertain? |
| Negative FH result | No reportable FH variant was found in the test performed. | Was there a known family variant, and did the kidney tumor or leiomyoma pattern suggest other testing? |
| Tumor-only FH finding | The FH change or FH-deficient tumor clue may be present only in tumor tissue rather than inherited DNA. | Is separate germline testing needed before relatives are told they may be at inherited risk? |
| Family variant testing | Relatives may be offered targeted testing when a confirmed familial pathogenic FH variant is known. | Does the report name the exact familial variant relatives should be tested for? |
Kidney and leiomyoma context to clarify
- NCI states that germline FH pathogenic-variant testing is indicated for people with HLRCC and for people suspected of having HLRCC, regardless of family history.
- MedlinePlus describes HLRCC as involving smooth-muscle tumors in the skin and uterus, plus increased risk for kidney cancer.
- GeneReviews notes that testing approaches can include single-gene testing, multigene panels, or broader genomic testing depending on the clinical and histopathologic picture.
- A tumor-only FH alteration, FH-deficient renal tumor clue, or tumor immunohistochemistry result may prompt germline evaluation, but it does not by itself prove inherited risk.
- A negative result is most reassuring when a known familial FH variant was specifically tested. Without a known family variant, it may be an uninformative negative.
Questions to bring to counseling
- Was FH tested from blood, saliva, cheek cells, tumor tissue, or paired tumor-normal testing?
- What is the exact FH variant notation and classification?
- Does the personal or family history include cutaneous leiomyomas, early or multiple uterine fibroids, FH-deficient kidney cancer, or kidney cancer at a young age?
- Would a positive germline result change kidney imaging, dermatology care, gynecology care, or family testing?
- Does the result raise any question about fumarase deficiency risk in children if both parents could carry FH variants?
- Could a tumor-only result require germline confirmation before family-risk decisions are made?
- How will I be notified if an FH VUS is reclassified?
When follow-up matters more
Follow-up becomes more important when kidney tumors, uterine fibroids, or skin leiomyomas are part of the picture, when a tumor-only finding needs germline confirmation, or when relatives may need targeted testing. In those situations, the result should be read as a kidney-risk and family-risk clue rather than a standalone answer.
Related guides: hereditary cancer genetic testing, tumor genomic vs inherited genetic testing, VHL genetic testing, BAP1 tumor predisposition genetic testing, and hereditary kidney disease genetic testing.
What the result still cannot prove
An FH result can support hereditary leiomyomatosis and renal cancer counseling, but it does not by itself predict exact tumor timing, severity, or whether another explanation also needs to be considered.
FAQ
Is FH mostly about kidney cancer?
FH can be important for kidney cancer risk, but it is also tied to cutaneous and uterine leiomyomas, so the full pattern matters.
Does a FH VUS change care?
No. A variant of uncertain significance should not be treated like a confirmed FH pathogenic variant.
Does a negative FH result rule out HLRCC?
Not always. A negative result does not fully rule it out if the clinical picture still fits the syndrome.
Does tumor-only FH prove inherited syndrome?
No. A tumor-only FH finding can support tumor interpretation but does not by itself prove inherited predisposition.
Should relatives be tested?
If a familial pathogenic FH variant is known, relatives may be offered targeted testing.
What should counseling clarify first?
The exact variant, kidney imaging history, leiomyoma history, and whether the report was from germline or tumor tissue.