Clinical molecular testing for VHLD has proven to be virtually 100% effective at detecting germline mutations in patients with pathology-proven disease.8 For this reason, molecular testing may be used to confirm a clinical diagnosis in an affected patient, screen for a mutation in an unaffected individual with a family history of VHLD, or rule out the disease in individuals with one VHLD-like tumor but no family history. When the mutation in the family is known, molecular testing may be used for predictive testing of at-risk family members or for prenatal testing.
A clinical diagnosis of VHLD may be made in an individual with at least two typical VHLD tumors with or without a family history of VHLD, or in an individual with at least one typical tumor and a significant family history.1 In such cases, a VHL gene mutation is almost invariably found. Identification of a mutation confirms the clinical diagnosis, establishes the need for periodic clinical screening, and facilitates predictive testing of at-risk relatives.
Predictive testing of at-risk family members for a known VHL gene mutation permits identification of presymptomatic mutation carriers and leads to early detection of tumors, timely intervention, and improved outcome. Identification of mutation-negative individuals eliminates the need for costly annual clinical screening. Genetic testing for a known VHL gene mutation is definitive.
Since the detection rate for germline mutations is so high, and since about 20% of patients have VHLD as the result of a sporadic mutation, testing is indicated in individuals with a single VHLD-type tumor and no family history of the disease. A negative-mutation screen greatly reduces the risk of VHLD in this circumstance. Since tumors have been reported in children as young as 4 years of age, and since the mutation status of at-risk individuals affects clinical care, predictive testing of asymptomatic children is appropriate. Prenatal testing for a VHL gene mutation is possible when the disease-causing mutation in an affected parent is known. However, prior to testing, consultation with a genetic counselor knowledgeable about the natural history of the disease and available treatment options is strongly recommended.
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