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Reviewed August 2014

What is the official name of the TPI1 gene?

The official name of this gene is “triosephosphate isomerase 1.”

TPI1 is the gene's official symbol. The TPI1 gene is also known by other names, listed below.

Read more about gene names and symbols on the About page.

What is the normal function of the TPI1 gene?

The TPI1 gene provides instructions for making an enzyme called triosephosphate isomerase 1. This enzyme is involved in a critical energy-producing process known as glycolysis. During glycolysis, the simple sugar glucose is broken down to produce energy for cells. The triosephosphate isomerase 1 enzyme carries out a specific reaction during glycolysis: the conversion of a molecule called dihydroxyacetone phosphate (DHAP) to glyceraldehyde 3-phosphate. This conversion can go both ways, meaning that the triosephosphate isomerase 1 enzyme can also convert glyceraldehyde 3-phosphate back into DHAP. Additional steps convert glyceraldehyde 3-phosphate into other molecules that ultimately produce energy in the form of a molecule called ATP.

For the triosephosphate isomerase 1 enzyme to be turned on (active), it has to attach (bind) to another triosephosphate isomerase 1 enzyme, forming a two-enzyme complex called a dimer.

How are changes in the TPI1 gene related to health conditions?

triosephosphate isomerase deficiency - caused by mutations in the TPI1 gene

At least 12 mutations in the TPI1 gene have been found to cause triosephosphate isomerase deficiency. This condition is characterized by a shortage of red blood cells (anemia), movement problems, increased susceptibility to infection, and muscle weakness that can affect breathing and heart function.

TPI1 gene mutations can lead to the production of an enzyme with decreased activity. As a result, glycolysis is impaired and cells have a decreased supply of energy. One TPI1 gene mutation accounts for approximately 80 percent of triosephosphate isomerase deficiency cases. This change replaces the protein building block (amino acid) glutamic acid with the amino acid aspartic acid at position 104 in the triosephosphate isomerase 1 enzyme (written as Glu104Asp or E104D). This mutation causes the enzyme to be unstable and impairs its ability to form a dimer and become active.

Red blood cells depend solely on the breakdown of glucose for energy. Without functional triosephosphate isomerase 1 enzyme to convert DHAP to glyceraldehyde 3-phosphate, red blood cells accumulate DHAP, which is toxic in large quantities. Unlike other cells, red blood cells do not have alternative pathways to break down DHAP. Due to the buildup of DHAP and the lack of cellular energy, red blood cells die earlier than normal.

Cells with high energy demands, such as nerve cells in the brain, white blood cells, and heart (cardiac) muscle cells are also susceptible to cell death due to reduced energy caused by impaired glycolysis. Nerve cells in the part of the brain involved in coordinating movements (the cerebellum) are particularly affected in people with triosephosphate isomerase deficiency. Death of red and white blood cells, nerve cells in the brain, and cardiac muscle cells leads to the signs and symptoms of triosephosphate isomerase deficiency.

Where is the TPI1 gene located?

Cytogenetic Location: 12p13

Molecular Location on chromosome 12: base pairs 6,867,420 to 6,870,946

(Homo sapiens Annotation Release 107, GRCh38.p2) (NCBIThis link leads to a site outside Genetics Home Reference.)

The TPI1 gene is located on the short (p) arm of chromosome 12 at position 13.

The TPI1 gene is located on the short (p) arm of chromosome 12 at position 13.

More precisely, the TPI1 gene is located from base pair 6,867,420 to base pair 6,870,946 on chromosome 12.

See How do geneticists indicate the location of a gene? in the Handbook.

Where can I find additional information about TPI1?

You and your healthcare professional may find the following resources about TPI1 helpful.

You may also be interested in these resources, which are designed for genetics professionals and researchers.

What other names do people use for the TPI1 gene or gene products?

  • TIM
  • TPI
  • TPID
  • triosephosphate isomerase
  • triose-phosphate isomerase

Where can I find general information about genes?

The Handbook provides basic information about genetics in clear language.

These links provide additional genetics resources that may be useful.

What glossary definitions help with understanding TPI1?

amino acid ; anemia ; aspartic acid ; ATP ; breakdown ; cardiac ; cell ; cerebellum ; deficiency ; dimer ; enzyme ; gene ; glucose ; glutamic acid ; infection ; molecule ; muscle cells ; mutation ; phosphate ; protein ; simple sugar ; susceptibility ; toxic ; white blood cells

You may find definitions for these and many other terms in the Genetics Home Reference Glossary.

See also Understanding Medical Terminology.

References (5 links)


The resources on this site should not be used as a substitute for professional medical care or advice. Users seeking information about a personal genetic disease, syndrome, or condition should consult with a qualified healthcare professional. See How can I find a genetics professional in my area? in the Handbook.

Reviewed: August 2014
Published: February 1, 2016