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Reviewed May 2010

What is the official name of the GTF2H5 gene?

The official name of this gene is “general transcription factor IIH subunit 5.”

GTF2H5 is the gene's official symbol. The GTF2H5 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 GTF2H5 gene?

The GTF2H5 gene provides instructions for making a protein called p8 or TTDA. This protein is one part (subunit) of a group of related proteins known as the general transcription factor IIH (TFIIH) complex. The TFIIH complex has two major functions: it is involved in the process of gene transcription, which is the first step in protein production, and it helps repair damaged DNA.

DNA can be damaged by ultraviolet (UV) rays from the sun and by toxic chemicals, radiation, and unstable molecules called free radicals. DNA damage occurs frequently, but normal cells are usually able to fix it before it can cause problems. One of the major mechanisms that cells use to fix DNA is known as nucleotide excision repair (NER). As part of this repair mechanism, the TFIIH complex opens up the section of double-stranded DNA that surrounds the damage. The TTDA protein helps with this process by stabilizing the TFIIH complex and maintaining its structure. Once the damaged region has been exposed, other proteins snip out (excise) the abnormal section and replace the damaged area with the correct DNA.

How are changes in the GTF2H5 gene related to health conditions?

trichothiodystrophy - caused by mutations in the GTF2H5 gene

At least three mutations in the GTF2H5 gene have been found to cause trichothiodystrophy. Mutations in this gene cause the photosensitive form of the condition, which is characterized by an extreme sensitivity to UV rays from sunlight.

Each of the known GTF2H5 gene mutations results in the production of a nonfunctional version of the TTDA protein. A loss of this protein probably causes the TFIIH complex to become unstable, which greatly reduces the amount of this complex within cells. Without enough of the TFIIH complex, cells cannot effectively repair DNA damage caused by UV radiation. These problems with DNA repair cause people with the photosensitive form of trichothiodystrophy to be extremely sensitive to sunlight. It is unclear how a loss of the TTDA protein leads to the other features of the condition, such as slow growth, intellectual disability, and brittle hair.

Where is the GTF2H5 gene located?

Cytogenetic Location: 6q25.3

Molecular Location on chromosome 6: base pairs 158,168,347 to 158,199,344

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

The GTF2H5 gene is located on the long (q) arm of chromosome 6 at position 25.3.

The GTF2H5 gene is located on the long (q) arm of chromosome 6 at position 25.3.

More precisely, the GTF2H5 gene is located from base pair 158,168,347 to base pair 158,199,344 on chromosome 6.

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

Where can I find additional information about GTF2H5?

You and your healthcare professional may find the following resources about GTF2H5 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 GTF2H5 gene or gene products?

  • bA120J8.2
  • C6orf175
  • FLJ30544
  • general transcription factor IIH, polypeptide 5
  • p8
  • TFB5
  • TFB5 ortholog
  • TFIIH basal transcription factor complex TTDA subunit
  • TFIIH basal transcription factor complex TTD-A subunit
  • TGF2H5
  • TTD
  • TTDA
  • TTD-A

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 GTF2H5?

disability ; DNA ; DNA damage ; DNA repair ; free radicals ; gene ; gene transcription ; NER ; nucleotide ; nucleotide excision repair ; protein ; radiation ; sensitivity ; subunit ; toxic ; transcription ; transcription factor ; UV rays

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

See also Understanding Medical Terminology.

References (9 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: May 2010
Published: February 1, 2016