• Turnaround time:
    10–21 calendar days (14 days on average)
  • Preferred specimen:
    3mL whole blood in a purple-top tube
  • Alternate specimens:
    DNA or saliva/assisted saliva
  • Sample requirements
  • Request a sample kit




Associated disorders

The QDPR gene is associated with autosomal recessive tetrahydrobiopterin-deficient hyperphenylalaninemia due to quinoid dihydropteridine reductase (DHPR) deficiency (MedGen UID: 75682).

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Invitae tests that include this gene:

An estimated 1-3% of hyperphenylalaninemia cases are due to defects in tetrahydrobiopterin metabolism. Of the 1-3% of cases, approximately 30% of them are due to quinoid dihydropteridine reductase deficiency (PMID: 19234759).

The QDPR gene encodes the enzyme quinoid dihydropteridine reductase; which catalyzes the NADH-mediated reduction of a quinonoid dihydrobiopterin to tetrahydrobiopterin (BH4). This is the second of two steps in the BH4 salvage pathway and following this reaction BH4 is available for reuse (PMID: 15171997).

Assay and technical information

Invitae is a College of American Pathologists (CAP)-accredited and Clinical Laboratory Improvement Amendments (CLIA)-certified clinical diagnostic laboratory performing full-gene sequencing and deletion/duplication analysis using next-generation sequencing technology (NGS).

Our sequence analysis covers clinically important regions of each gene, including coding exons, +/- 10 base pairs of adjacent intronic sequence, and select noncoding variants. Our assay provides a Q30 quality-adjusted mean coverage depth of 350x (50x minimum, or supplemented with additional analysis). Variants classified as pathogenic or likely pathogenic are confirmed with orthogonal methods, except individual variants that have high quality scores and previously validated in at least ten unrelated samples.

Our analysis detects most intragenic deletions and duplications at single exon resolution. However, in rare situations, single-exon copy number events may not be analyzed due to inherent sequence properties or isolated reduction in data quality. If you are requesting the detection of a specific single-exon copy number variation, please contact Client Services before placing your order.

Gene Transcript reference Sequencing analysis Deletion/Duplication analysis
QDPR NM_000320.2