The Generative Brain

PRNP gene sequencing (diagnostic and predictive)

PRNP sequencing reads the prion protein gene in DNA from blood, saliva, a cheek swab or autopsy tissue. It is an established clinical test offered by a US national center, units in the UK and Australia and several commercial laboratories; the main trap is the octapeptide repeat region, which NGS panels usually miss. Counseling before any predictive use is the recognised standard. Information only, not advice.

Key facts

  • PRNP variants cause roughly 10 to 15 percent of prion disease, and the test finds pathogenic changes in the single gene behind genetic prion disease.
  • GeneReviews lists PRNP sequence analysis as detecting 100 percent of probands with a pathogenic variant; the footnotes behind the figure were not read.
  • US national center (NPDPSC, Cleveland): PCR plus bidirectional sequencing, 15 business days from receipt, not available STAT, not performed under age 18.
  • US cost: the basic cost is USD 274.83, stated as applying if blood is sent for a patient without a confirmed family history of genetic CJD (policy effective 1 August 2011); predictive testing was free for first-degree relatives of a confirmed case at the time of a 2022 review.
  • US logistics: two 5 ml EDTA tubes at room temperature, shipped Monday to Thursday only; the family history form and a genetic consent form must accompany the order.
  • Commercial NGS (Fulgent example): sequencing and copy number detection in 2 to 3 weeks that excludes the octapeptide repeat region; a separate repeat-primed PCR assay takes 2 weeks and does not include full sequencing.
  • UCL MRC Prion Unit sequences the full coding region or the octapeptide repeat region specifically; standard sequencing can miss repeat insertions.
  • Australia: testing is voluntary, run at PathWest Neurogenetics in Nedlands, and no price or turnaround is listed on the registry page.
  • India: DNA Labs India lists an NGS PRNP test at INR 20,000 with a 3 to 4 week report; vendor material that does not say whether repeat insertions are detected.
  • UK: the National Prion Clinic is the national referral centre, but its landing page states no test, fee or turnaround.
  • The NPDPSC lab test directory copy of the PRNP test page lists CPT 81404, USD 274.83, an analytic time of 15 business days, no testing under age 18, two 5 ml EDTA tubes, Monday to Thursday overnight shipping and required request and genetic consent forms.
  • An older copy of the same test page on the center site describes sequencing of PRNP exon 2 with an analytic time of 30 business days and says patients under 18 need documented medical necessity approved by the director; the price is the same.
  • The center's autopsy testing and reporting page says blood PRNP sequencing takes about 14 days from receipt and that results cannot be released without a signed testing and reporting form; the three copies conflict on turnaround, so confirm with the center before planning.
  • The USD 274.83 charge is stated as applying if blood is submitted for a patient without a confirmed family history of genetic CJD, under a policy effective 1 August 2011; the 2025 and 2026 requisition forms say the center offers MRI interpretation at no cost.

Timeline

  1. 2011NPDPSC fee policy effective.
  2. 2021GeneReviews entry last updated.
  3. 2022Goldman and Vallabh counseling review available online.
  4. 2025NPDPSC blood PRNP page last updated.
  5. 2026Genetic test requisition and consent forms updated on the center site.
  6. 2026Depth pass: NPDPSC, Florey, Fulgent, DNA Labs India, GeneReviews and UCL pages read.
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