Meyahealth
HomeGeneticsGeneGTF2H5 gene
Back to Gene
GTF2H5 gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

GTF2H5 gene

The GTF2H5 gene provides instructions for a protein essential to the TFIIH complex, which is critical for gene transcription and repairing damaged DNA.

Normal Function

The GTF2H5 gene provides instructions for making a protein called p8 or TTDA. This protein is a subunit of the general transcription factor 2 H (TFIIH) complex. The TFIIH complex performs two major roles: facilitating gene transcription (the first step in protein production) and repairing damaged DNA.

Cells frequently experience DNA damage from sources like ultraviolet (UV) rays or toxic chemicals. One primary repair mechanism is nucleotide excision repair (NER). During this process, the TFIIH complex opens the double-stranded DNA surrounding the damage. The TTDA protein stabilizes the TFIIH complex and maintains its structure, allowing other proteins to excise the damaged section and replace it with correct DNA.

Health Conditions Related to Genetic Changes

Trichothiodystrophy

Variants in the GTF2H5 gene can cause the photosensitive form of trichothiodystrophy. This condition is characterized by sparse, brittle hair and extreme sensitivity to UV rays from sunlight.

These genetic variants result in a nonfunctional TTDA protein, which causes the TFIIH complex to become unstable and reduces its overall amount within cells. Consequently, cells cannot effectively repair DNA damage caused by UV exposure. While the link between the loss of TTDA and sunlight sensitivity is clear, it remains unclear how this deficiency leads to other symptoms such as slow growth and intellectual disability.

Frequently Asked Questions

Most cases of TTD caused by GTF2H5 are autosomal recessive. Both parents are typically carriers of one mutated copy and have no symptoms. Siblings have a 25 % chance of being affected, a 50 % chance of being carriers, and a 25 % chance of being unaffected non‑carriers. Offer carrier testing to parents and at‑risk relatives, and discuss reproductive options such as preimplantation genetic testing if desired.
The presentation suggests the photosensitive form of trichothiodystrophy (TTD). Diagnosis begins with a clinical evaluation of hair microscopy (tiger‑stripe pattern) and skin photosensitivity, followed by molecular testing—usually targeted sequencing or a deletion/duplication panel that includes GTF2H5. Confirmation of pathogenic variants in both alleles establishes the diagnosis.
Rigorous UV protection is essential: apply broad‑spectrum sunscreen (SPF 50+) every 2 hours, wear UV‑blocking clothing (long sleeves, wide‑brim hat, UV‑rated fabrics), use sunglasses with 100 % UVA/UVB protection, and seek shade whenever possible. Indoor lighting should also be filtered for UV (e.g., using UV‑blocking window films). Even with protection, limit direct sun exposure to the minimum needed for vitamin D, and discuss supplementation with your physician.
Currently, there is no therapy that restores the defective TFIIH complex. Management focuses on preventing DNA damage (sun protection, avoiding mutagenic chemicals) and addressing secondary complications—such as hair care with gentle, protein‑rich shampoos, monitoring growth and developmental milestones, and providing educational support. Research into gene‑replacement or small‑molecule stabilizers of TFIIH is ongoing but not yet clinically available.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

Meyahealth

Ⓒ 2026. All rights reserved by MEYA

About UsTerms & PolicyFAQ