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Xanthinuria Type I via the XDH 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
XDH 81479 81479,81479 $990
Test Code Test Copy Genes Test CPT Code Gene CPT Codes Copy CPT Code Base Price
11863XDH81479 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. If the Sanger option is selected, CNV detection may be ordered through Test #600.

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

Xanthinuria is characterized by the accumulation of xanthine in serum and urine (Dent and Philpot, 1954. PubMed ID: 13118765; Raivio et al., 2014). Patients also present with hypouricaemia and hypouricosuria due to insufficient breakdown of xanthine (Raivio et al., 2014). Affected individuals may develop urinary xanthine calculi leading to hematuria, crystalluria, and renal colic (Bradbury et al., 1995. PubMed ID: 7577413; Carpenter et al., 1986. PubMed ID: 3755469). Clinical variability is observed and only ~50% of patients develop urolithiasis. Xanthinuria type I occasionally presents with muscle pains and cramps due to xanthine deposition (Chalmers et al., 1969. PubMed ID: 4902314; Parker et al., 1970. PubMed ID: 5414104). Xanthinuria Type II is characterized by deficiency in xanthine dehydrogenase and aldehyde oxidase due to pathogenic variants in the molybdenum cofactor sulfurase, MOCOS, gene. Although the two types have similar clinical presentation, a distinction between the two types is based on the ability to oxidize allopurinol to oxypurinol.


Xanthinuria Type I is a rare autosomal recessive disorder caused by pathogenic variants in the XDH gene located on chromosome 2p23.1. The XDH gene encodes xanthine dehydrogenase (1333 amino acids, MW 146 kDa) which is functional as a homodimer. The xanthine dehydrogenase enzyme catalyzes two independent steps in purine metabolism: the oxidation of hypoxanthine to xanthine and xanthine to uric acid. The N-terminal 20-kDA domain contains two non-identical Fe-S clusters, the middle 40-kDa contains an FAD center, and the C-terminal 85-kDa domain binds molybdenum cofactor. Pathogenic variants include missense, nonsense, and small frameshift deletions or insertions (Arikyants et al., 2006. PubMed ID: 17115198; Eggermann et al., 2013. PubMed ID: 23249873; Ichida et al., 1997. PubMed ID: 9153281; Levartovsky et al., 2000. PubMed ID: 10844591; Nakamura et al., 2012. PubMed ID: 22981351; Sakamoto et al., 2001. PubMed ID: 11379872; Stiburkova et al., 2012. PubMed ID: 21963464; Human Gene Mutation Database). Incidence estimates range from 1 in 6,000 to 1 in 69,000 (Harkness et al., 1983. PubMed ID: 6422142; Harkness et al., 1986. PubMed ID: 3104682). This large range may reflect the rarity of the disease and population differences. Xanthinuria may be more prevalent in Mediterranean countries (Raivio et al., 2014).

Clinical Sensitivity - Sequencing with CNV PGxome

Clinical sensitivity cannot be estimated because only a small number of patients have been reported. Analytical sensitivity should be high because the great majority of pathogenic variants reported are detectable by sequencing.

Clinical sensitivity for Copy Number Variants will likely be low since only one gross deletion has been reported to date (Eggermann et al., 2013. PubMed ID: 23249873).

Testing Strategy

This test provides full coverage of all coding exons of the XDH 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

Candidates for this test are patients with plasma uric acid levels below 5 μM and plasma xanthine over 10 μM and normal metabolism of allopurinol. Testing is also indicated for family members of patients who have known XDH pathogenic variants. This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in XDH.


Official Gene Symbol OMIM ID
XDH 607633
Inheritance Abbreviation
Autosomal Dominant AD
Autosomal Recessive AR
X-Linked XL
Mitochondrial MT


Name Inheritance OMIM ID
Xanthinuria, Type I AR 278300


  • Arikyants et al., 2006. PubMed ID: 17115198
  • Bradbury et al., 1995. PubMed ID: 7577413
  • Carpenter et al., 1986. PubMed ID: 3755469
  • Chalmers et al., 1969. PubMed ID: 4902314
  • Dent and Philpot, 1954. PubMed ID: 13118765
  • Eggermann et al., 2013. PubMed ID: 23249873
  • Harkness et al., 1983. PubMed ID: 6422142
  • Harkness et al., 1986. PubMed ID: 3104682
  • Human Gene Mutation Database (Bio-base).
  • Ichida et al., 1997. PubMed ID: 9153281
  • Levartovsky et al., 2000. PubMed ID: 10844591
  • Nakamura et al., 2012. PubMed ID: 22981351
  • Parker et al., 1970. PubMed ID: 5414104
  • Raivio et al., 2014. Xanthine Oxidoreductase—Role in Human Pathophysiology and in Hereditary Xanthinuria. The Online Metabolic and Molecular Bases of Inherited Disease, New York, NY: The McGraw-Hill Companies, Inc.
  • Sakamoto et al., 2001. PubMed ID: 11379872
  • Stiburkova et al., 2012. PubMed ID: 21963464


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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Note: acceptable specimen types are whole blood and DNA from whole blood only.
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