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Dihydropteridine Reductase (DHPR) Deficiency via the QDPR Gene

Summary and Pricing

Test Method

Exome Sequencing with CNV Detection
Test Code Test Copy GenesTest CPT Code Gene CPT Codes Copy CPT Codes Base Price
QDPR 81479 81479,81479 $990
Test Code Test Copy Genes Test CPT Code Gene CPT Codes Copy CPT Code Base Price
11891QDPR81479 81479,81479 $990 Order Options and Pricing

Pricing Comments

Our favored testing approach is exome based NextGen sequencing with CNV analysis. This will allow cost effective reflexing to PGxome or other exome based tests. However, if full gene Sanger sequencing is desired for STAT turnaround time, insurance, or other reasons, please see link below for Test Code, pricing, and turnaround time information.

An additional 25% charge will be applied to STAT orders. STAT orders are prioritized throughout the testing process.

Click here for costs to reflex to whole PGxome (if original test is on PGxome Sequencing platform).

Click here for costs to reflex to whole PGnome (if original test is on PGnome Sequencing platform).

The Sanger Sequencing method for this test is NY State approved.

For Sanger Sequencing click here.

Turnaround Time

3 weeks on average for standard orders or 2 weeks on average for STAT orders.

Please note: Once the testing process begins, an Estimated Report Date (ERD) range will be displayed in the portal. This is the most accurate prediction of when your report will be complete and may differ from the average TAT published on our website. About 85% of our tests will be reported within or before the ERD range. We will notify you of significant delays or holds which will impact the ERD. Learn more about turnaround times here.

Targeted Testing

For ordering sequencing of targeted known variants, go to our Targeted Variants page.


Genetic Counselors


  • McKenna Kyriss, PhD

Clinical Features and Genetics

Clinical Features

Hyperphenylalaninemias due to tetrahydrobiopterin (BH4) deficiency are a result of a disruption in phenylalanine homeostasis and dopamine and serotonin biosynthesis. These disorders are caused by pathogenic variants in the genes encoding enzymes involved in the biosynthesis or regeneration of BH4. The phenylalanine, tyrosine, and tryptophan hydroxylases all require BH4 as a cofactor, and lack of this cofactor results in secondary hyperphenylalaninemia and depletion of the neurotransmitters dopamine and serotonin. Early detection and treatment can reduce neurologic symptoms (Blau et al. 2014).

Patients with dihydropteridine reductase (DHPR) deficiency are usually detected via newborn screening due to hyperphenylalaninemia. Urinary pterin profiles and DHPR activity in dry blood spots on Guthrie cards are widely used for the clinical diagnosis of DHPR deficiency (Blau et al. 2014, Trujillano et al. 2014). These patients are unresponsive to a phenylalanine-restricted diet and develop severe neurologic symptoms including psychomotor retardation, delayed development, tonal abnormalities, seizures, and dystonia. Patients may also present with abnormal thermogenesis, microcephaly, swallowing difficulties and hypersalivation. Symptoms will become apparent typically between birth and four months of age (Blau et al. 2014, Trujillano et al. 2014).


Dihydropteridine reductase deficiency is inherited in an autosomal recessive manner. The QDPR gene (chromosome 4p15.3, 7 exons) encodes the DHPR enzyme which is involved in the regeneration of tetrahydrobiopterin from quinonoid dihydropteridine (Smooker and Cotton 1995). Reported pathogenic variants include mostly missense with some nonsense, splicing, and small insertions/deletions (Human Gene Mutation Database). Pathogenic variants are spread evenly along the coding sequence. Some of these variants have been mapped to the NADH binding domain of the protein (Smooker and Cotton 1995). Other inborn errors of BH4 metabolism can present with a similar clinical course and involve 6-pyruvoyl tetrahydropterin synthase (PTS gene), GTP cyclohydrolase I (GCH1 gene), and pterin-4α-carbinalamine dehydratase (PCBD1 gene) (Blau et al. 2014, Trujillano et al. 2014).

Clinical Sensitivity - Sequencing with CNV PGxome

Near 100% clinical sensitivity. In a collective total of 30 patients from different families with a clinical diagnosis of dihydropteridine reductase (DHPR) deficiency, all patients were found to be homozygous or compound heterozygous for pathogenic variants (Romstad et al. 2000; Smooker et al. 1999; Dianzani et al. 1998). Analytical sensitivity should also be close to 100% because all reported pathogenic variants thus far are detectable by sequencing.

Testing Strategy

This test provides full coverage of all coding exons of the QDPR gene plus 10 bases of flanking noncoding DNA in all available transcripts along with other non-coding regions in which pathogenic variants have been identified at PreventionGenetics or reported elsewhere. We define full coverage as >20X NGS reads or Sanger sequencing. PGnome panels typically provide slightly increased coverage over the PGxome equivalent. PGnome sequencing panels have the added benefit of additional analysis and reporting of deep intronic regions (where applicable).

Dependent on the sequencing backbone selected for this testing, discounted reflex testing to any other similar backbone-based test is available (i.e., PGxome panel to whole PGxome; PGnome panel to whole PGnome).

Indications for Test

Newborn screening indicative of hyperpheylalaninemia. Patients with decreased homovanillic acid (HVA) and 5-hydroxyindoleacetic acid (5HIAA) in CSF, increased biopterin in urine and CSF, or decreased/absent dihydropteridine reductase activity. This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in QDPR.


Official Gene Symbol OMIM ID
QDPR 612676
Inheritance Abbreviation
Autosomal Dominant AD
Autosomal Recessive AR
X-Linked XL
Mitochondrial MT


Name Inheritance OMIM ID
Dihydropteridine Reductase Deficiency AR 261630

Related Tests

6-Pyruvoyltetrahydropterin Synthase (PTPS) Deficiency via the PTS Gene
Hyperphenylalaninemia Panel
Sepiapterin Reductase (SR) Deficiency via the SPR Gene


  • Blau N.et al. 2014. Disorders of Tetrahydrobiopterin and Related Biogenic Amines. Online Metabolic & Molecular Bases of Inherited Disease, New York, NY: McGraw-Hill.
  • Dianzani I, Sanctis L de, Smooker PM, Gough TJ, Alliaudi C, Brusco A, Spada M, Blau N, Dobos M, Zhang H-P, Yang N, Ponzone A, Armarego WL, Cotton RG. 1998. Dihydropteridine reductase deficiency: Physical structure of the QDPR gene, identification of two new mutations and genotype–phenotype correlations. Hum. Mutat. 12: 267-273. PubMed ID: 9744478
  • Human Gene Mutation Database (Bio-base).
  • Romstad A, Kalkanoglu HS, Coskun T, Demirkol M, Tokatli A, Dursun A, Baykal T, Ozalp I, Guldberg P, Güttler F. 2000. Molecular analysis of 16 Turkish families with DHPR deficiency using denaturing gradient gel electrophoresis (DGGE). Hum. Genet. 107: 546-553. PubMed ID: 11153907
  • Smooker PM, Cotton RGH. 1995. Molecular basis of dihydropteridine reductase deficiency. Hum. Mutat. 5: 279–284. PubMed ID: 7627180
  • Smooker PM, Gough TJ, Cotton RGH, Alliaudi C, Sanctis L de, Dianzani I. 1999. A series of mutations in the dihydropteridine reductase gene resulting in either abnormal RNA splicing or DHPR protein defects. Hum. Mutat. 13: 503-504. PubMed ID: 10408783
  • Trujillano D. et al. 2014. European Journal of Human Genetics : Ejhg. 22: 528-34. PubMed ID: 23942198


Ordering Options

We offer several options when ordering sequencing tests. For more information on these options, see our Ordering Instructions page. To view available options, click on the Order Options button within the test description.

myPrevent - Online Ordering

  • The test can be added to your online orders in the Summary and Pricing section.
  • Once the test has been added log in to myPrevent to fill out an online requisition form.
  • PGnome sequencing panels can be ordered via the myPrevent portal only at this time.

Requisition Form

  • A completed requisition form must accompany all specimens.
  • Billing information along with specimen and shipping instructions are within the requisition form.
  • All testing must be ordered by a qualified healthcare provider.

For Requisition Forms, visit our Forms page

If ordering a Duo or Trio test, the proband and all comparator samples are required to initiate testing. If we do not receive all required samples for the test ordered within 21 days, we will convert the order to the most effective testing strategy with the samples available. Prior authorization and/or billing in place may be impacted by a change in test code.

Specimen Types

Specimen Requirements and Shipping Details

PGxome (Exome) Sequencing Panel

PGnome (Genome) Sequencing Panel

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