Sanger Sequencing of VHL Only for Von Hippel-Lindau Syndrome (VHL1)
Information for Ordering
{slide=Acceptable Specimen Types}• Fresh blood sample (3-6 ml EDTA; no time limitations associated with receipt)
• DNA (extracted from lymphocyte cells; a minimum volume of 25μL at 3μg; O.D. of 260:280nm ≥1.8; must be extracted in a CLIA or equivalent certified lab)
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Average = 15 working days
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$650 (USD – institutional/self-pay price)
CPT: 81404 and 81403
Z code: ZB68F
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{slide=Candidates for Testing}
Patients seeking confirmation of a clinical diagnosis of VHL with only one of the characteristic manifestations.
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Please find specimen requirement specifications above.
All submitted specimens must be sent at room temperature. DO NOT ship on ice.
Specimens must be packaged to prevent breakage and absorbent material must be included in the package to absorb liquids in the event that breakage occurs. Also, the package must be shipped in double watertight containers (e.g. a specimen pouch + the shipping company’s diagnostic envelope).
To request a sample collection kit, please click here or email medgenomics@uabmc.edu to complete the specimen request form.
Please contact the MGL (via email at medgenomics@uabmc.edu, or via phone at 205-934-5562) prior to sample shipment and provide us with the date of shipment and tracking number of the package so that we can better ensure receipt of the samples.
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Form for Customs
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About
{slide=Disorder Background}VHL syndrome is an autosomal dominant disorder with a high penetrance (almost complete by 60 years of age) characterized by hemangioblastomas in central nervous system (CNS), retina and other visceral organs. This disorder is also associated with an increased risk of other tumors including clear cell carcinomas of the kidney, pheochromocytoma, renal cysts, pancreatic cystadenoma and pancreatic neuroendocrine tumors. VHL affects ~ 1:35,000 individuals. World-wide prevalence of VHL is approximately 1: 36,000 live births. All ethnic groups and both sexes are affected equally.
The official name for the VHL gene is von Hippel-Lindau tumor suppressor, which resides on chromosome 3p25.3. VHL gene contains 3 exons and encodes a ~ 4.5 kb mRNA. Loss of function variants in VHL are the only known cause of VHL, and germline VHL variants can be detected in up to 100% of VHL families. Germline variants are scattered throughout the coding region of the gene. Missense variants (leading to an amino acid substitution in the VHL protein product) are found in 40 % of the families with an identified VHL germline variant. Microdeletions (1-18 bp.), insertions (1-8 bp.), splice site and nonsense variants, predicted to lead to a truncated protein, are found in approximately 30 % of the families. Large deletions account for one-third of the VHL germline variants, of which approximately 30 % (or some 10 % of all VHL germline variants) are deletions encompassing the entire gene. The de novo variant rate is estimated at 20% and mosaicism may occur in a small percentage of VHL patients.
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The VHL-only by Sanger sequencing starts with extraction of DNA from the blood sample of the patient, followed by amplification of three exon fragments. These PCR fragments encompassing the entire VHL coding region are hereafter used as the template for direct bi-directional cycle sequencing (Tier 1). MLPA analysis (Tier 2) is also performed to detect copy number changes, such as multi-exon deletions or duplications and total gene deletions.
REFERENCES available here.
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For more information, test requisition forms, or sample collection and mailing kits, please call: 205-934-5562.