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Genetics Home Reference: your guide to understanding genetic conditions     A service of the U.S. National Library of Medicine®


Reviewed August 2008

What is the official name of the JPH3 gene?

The official name of this gene is “junctophilin 3.”

JPH3 is the gene's official symbol. The JPH3 gene is also known by other names, listed below.

What is the normal function of the JPH3 gene?

The JPH3 gene provides instructions for making a protein called junctophilin-3, which is found primarily in the brain. Although the exact function of this protein is unclear, researchers believe that it plays a role in the formation of a structure called the junctional membrane complex. This complex connects certain channels inside cells with other channels at the cell surface. The junctional membrane complex appears to be involved in the release of charged calcium atoms (calcium ions), which are critical for transmitting signals within cells. As part of the junctional membrane complex, junctophilin-3 is probably involved in signaling within and between nerve cells (neurons) in the brain.

One region of the JPH3 gene contains a particular DNA segment known as a CAG/CTG trinucleotide repeat. This segment is made up of a series of three DNA building blocks (nucleotides) that appear multiple times in a row. Normally, the CAG/CTG segment is repeated 6 to 28 times within the gene.

How are changes in the JPH3 gene related to health conditions?

Huntington disease-like syndrome - caused by mutations in the JPH3 gene

A particular type of mutation in the JPH3 gene has been found to cause signs and symptoms that resemble those of Huntington disease, including uncontrolled movements, emotional problems, and loss of thinking ability. Researchers have named this condition Huntington disease-like 2 (HDL2).

The mutation associated with HDL2 increases the size of the CAG/CTG trinucleotide repeat in the JPH3 gene. People with this condition have 44 to 59 CAG/CTG repeats. People with 29 to about 43 CAG/CTG repeats may or may not develop the signs and symptoms of HDL2.

Researchers are working to determine the effects of the abnormally large CAG/CTG segment. They believe that the mutated JPH3 gene produces an altered version of messenger RNA, which is a molecular blueprint of the gene that is normally used for protein production. The abnormal messenger RNA forms clumps inside neurons that interfere with the normal functions of these cells. The dysfunction and eventual death of neurons in certain areas of the brain underlie the signs and symptoms of HDL2.

Where is the JPH3 gene located?

Cytogenetic Location: 16q24.3

Molecular Location on chromosome 16: base pairs 87,601,835 to 87,698,156

(Homo sapiens Annotation Release 107, GRCh38.p2) (NCBI (

The JPH3 gene is located on the long (q) arm of chromosome 16 at position 24.3.

The JPH3 gene is located on the long (q) arm of chromosome 16 at position 24.3.

More precisely, the JPH3 gene is located from base pair 87,601,835 to base pair 87,698,156 on chromosome 16.

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

Where can I find additional information about JPH3?

You and your healthcare professional may find the following resources about JPH3 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 JPH3 gene or gene products?

  • CAGL237
  • FLJ44707
  • HDL2
  • JP3
  • JP-3
  • junctophilin-3
  • junctophilin type 3
  • TNRC22
  • trinucleotide repeat containing 22

See How are genetic conditions and genes named? ( in the Handbook.

What glossary definitions help with understanding JPH3?

calcium ; cell ; DNA ; endoplasmic reticulum ; gene ; ions ; messenger RNA ; mRNA ; mutation ; protein ; RNA ; syndrome ; trinucleotide repeat

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


  • Greenstein PE, Vonsattel JP, Margolis RL, Joseph JT. Huntington's disease like-2 neuropathology. Mov Disord. 2007 Jul 30;22(10):1416-23. (
  • Margolis RL, O'Hearn E, Rosenblatt A, Willour V, Holmes SE, Franz ML, Callahan C, Hwang HS, Troncoso JC, Ross CA. A disorder similar to Huntington's disease is associated with a novel CAG repeat expansion. Ann Neurol. 2001 Dec;50(6):373-80. (
  • NCBI Gene (
  • Nishi M, Mizushima A, Nakagawara Ki, Takeshima H. Characterization of human junctophilin subtype genes. Biochem Biophys Res Commun. 2000 Jul 14;273(3):920-7. (
  • Rudnicki DD, Pletnikova O, Vonsattel JP, Ross CA, Margolis RL. A comparison of huntington disease and huntington disease-like 2 neuropathology. J Neuropathol Exp Neurol. 2008 Apr;67(4):366-74. doi: 10.1097/NEN.0b013e31816b4aee. (
  • Takeshima H, Komazaki S, Nishi M, Iino M, Kangawa K. Junctophilins: a novel family of junctional membrane complex proteins. Mol Cell. 2000 Jul;6(1):11-22. (
  • Walker RH, Jankovic J, O'Hearn E, Margolis RL. Phenotypic features of Huntington's disease-like 2. Mov Disord. 2003 Dec;18(12):1527-30. (


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 2008
Published: February 8, 2016