Table 1.

Summary of Molecular Genetic Testing Used in the Diagnosis of Genetic Prion Diseases

Gene 1Test MethodAllelic Variants Detected 2Variant Detection Frequency by Test Method 3
PRNPSequence analysis 4Sequence variantsUnknown 5
Targeted analysis for pathogenic variantsDuplication of 1 to 9 additional octapeptide repeats (Pro-His-Gly-Gly-Gly-Trp-Gly-Gln)Unknown
1.
2.

See Molecular Genetics for information on allelic variants.

3.

The ability of the test method used to detect a variant that is present in the indicated gene

4.

Examples of pathogenic variants detected by sequence analysis may include small intragenic deletions/insertions and missense, nonsense, and splice site variants; typically, exon or whole-gene deletions/duplications are not detected. For issues to consider in interpretation of sequence analysis results, click here.

5.

By definition, "genetically transmissible" prion disease requires the presence of a pathogenic PRNP variant; however, it is possible that sequence analysis of the coding and flanking intronic regions does not detect all pathogenic variants. Thus, the absence of a pathogenic variant does not rule out the diagnosis.

From: Genetic Prion Diseases

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