Table 1.
Mutations in the NER pathway and corresponding clinical sequela
| Gene | Normal protein function | Clinical syndrome | Disease characteristics |
|---|---|---|---|
| XPA | Protein that assists with DNA unwinding | XP-A | Photosensitivity, poikiloderma, lentigines, skin cancer, neurodegeneration |
| XPB/ ERCC3 | Helicase involved with DNA unwinding | XP-B, CS, TTD | Photosensitivity, poikiloderma, lentigines, skin cancer, neurodegeneration |
| XPC | Protein recognizing global genome defects | XP-C | Photosensitivity, poikiloderma, lentigines, skin cancer |
| XPD/ ERCC2 | Helicase involved with DNA unwinding | XP-D, TTD, COFS, CS | Photosensitivity, poikiloderma, lentigines, skin cancer, neurodegeneration, brain tumors |
| XPE/ DDB2 | Protein recognizing global genome defects | XP-E | Photosensitivity, poikiloderma, lentigines, skin cancer, neurodegeneration |
| XPF/ ERCC4 | Forms an endonuclease together with ERCC1 that incises damaged DNA for repair | XP-F, XFE progeroid syndrome, Fanconi anemia | Photosensitivity, poikiloderma, lentigines, skin cancer, neurodegeneration, brain tumors |
| XPG/ ERCC5 | Endonuclease that incise damaged DNA | XP-G | Photosensitivity, poikiloderma, lentigines, skin cancer, neurodegeneration |
| XPV/ POLH | DNA-polymerase eta (pol-eta) which performs trans-lesion DNA synthesis past ultraviolet (UV) | XP Variant | Milder photosensitivity and poikiloderma |
| ERCC1 | Forms an endonuclease together with XPF/ ERCC4 that incises damaged DNA for repair | XP, CS, COFS | Photosensitivity, poikiloderma, lentigines, skin cancer, neurodegeneration |
| CSA/ERCC8 | DNA excision repair protein involved in the TCR pathways | CS | Growth failure, impaired neurodevelopment, photosensitivity, eye disorders, premature aging |
| CSB/ ERCC6 | DNA excision repair protein involved in the TCR pathway | CS, COFS | Growth failure, severely impaired neurodevelopment, photosensitivity, eye disorders, premature aging |
| GTF2H5 | TTDA protein stabilizes the DNA/protein complex during unwinding of DNA strand for repair | TTD | Brittle hair, intellectual impairment, photosensitivity |
| TTDN1/ C7orf11 | Regulates mitosis and cytokinesis | TTD | Non-photosensitive TTD |