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Triosephosphate Isomerase Deficiency via the TPI1 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
TPI1 81479 81479,81479 $990
Test Code Test Copy Genes Test CPT Code Gene CPT Codes Copy CPT Code Base Price
8611TPI181479 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


  • Luke Drury, PhD

Clinical Features and Genetics

Clinical Features

Triosephosphate isomerase (TPI) deficiency has been reported in less than 100 individuals. TPI deficiency is a metabolic disorder due to impairment of the glycolytic pathway. Patients present in early childhood with life threatening chronic hemolytic anemia and progressive neuromuscular impairment. Additional symptoms can include cardiomyopathy, susceptibility to chronic infections, splenomegaly, dyspnea, jaundice and fatigue (Orosz et al. 2006). Genetic testing can be helpful in the differential diagnosis of TPI deficiency from other forms of hemolytic anemia including thalassemia, spherocytosis, glucose-6-phosphate dehydrogenase deficiency, pyruvate kinase deficiency, and acquired and immune hemolytic anemias. There are no curative therapies for TPI deficiency, but supportive care includes blood transfusions and assisted ventilation (Orosz et al. 2009).


TPI deficiency is inherited in an autosomal recessive manner through pathogenic variants in the TPI1 gene. The TPI1 gene encodes triosephosphate isomerase which is a glycolytic enzyme that regulates dihydroxyacetone phosphate (DHAP) and glyceraldehyde-3-phosphate equilibrium. TPI functions as a homodimer and when disrupted, leads to DHAP accumulation which is metabolized to toxic methylglyoxal. The c.315G>C (p.Glu105Asp), also referred to as p.Glu104Asp using legacy nomenclature, is the most prevalent pathogenic variant and accounts for about 80% of causative alleles (Daar et al. 1986; Orosz et al. 2009, Watanabe et al. 1996). Other missense variants have also been reported through the coding region which impair TPI dimer formation (Orosz et al. 2006). Nonsense, small insertions and deletions have also been reported in a minority of cases (Valentin et al. 2000). TPI deficiency is fully penetrant with symptom onset occurring during infancy (Orosz et al. 2009).

Clinical Sensitivity - Sequencing with CNV PGxome

Clinical sensitivity cannot be estimated because only a small number of cases have been reported to date. Analytical sensitivity should be high because all pathogenic variants to date are detected by this method.

Testing Strategy

This test provides full coverage of all coding exons of the TPI1 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 testing include patients presenting with hemolytic anemia and neurologic impairment consistent with TPI deficiency. Other characteristics of TPI deficiency include decreased TPI activity in red blood cells (<50%) and heightened dihydroxyacetone phosphate (DHAP) (Orosz et al. 2006). This test may also be considered for the reproductive partners of individuals who carry pathogenic variants in TPI1.


Official Gene Symbol OMIM ID
TPI1 190450
Inheritance Abbreviation
Autosomal Dominant AD
Autosomal Recessive AR
X-Linked XL
Mitochondrial MT


  • Daar I.O. et al. 1986. Proceedings of the National Academy of Sciences of the United States of America. 83: 7903-7. PubMed ID: 2876430
  • Orosz F. et al. 2006. Iubmb Life. 58: 703-15. PubMed ID: 17424909
  • Orosz F. et al. 2009. Biochimica Et Biophysica Acta. 1792: 1168-74. PubMed ID: 19786097
  • Valentin C. et al. 2000. Blood. 96: 1130-5. PubMed ID: 10910933
  • Watanabe M. et al. 1996. American Journal of Human Genetics. 58: 308-16. PubMed ID: 8571957


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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View Ordering Instructions

1) Select Test Method (Platform)

1) Select Test Type

2) Select Additional Test Options

No Additional Test Options are available for this test.

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