Here I present: “Xeroderma Pigmentosum”, Victor McKusick, Mendelian Inheritance in Man’, 1966. 色素性對皮。(XP) icd10=Q82.1
INTRODUCTION.
Xeroderma pigmentosum (XP) is a genetic disorder in which there is a decreased ability to repair DNA damage such as that caused by ultraviolet (UV) light. Symptoms may include a severe sunburn after only a few minutes in the sun, freckling in sun-exposed areas, dry skin and changes in skin pigmentation. Nervous system problems, such as hearing loss, poor coordination, loss of intellectual function and seizures, may also occur. Complications include a high risk of skin cancer, with about half having skin cancer by age 10 without preventative efforts, and cataracts. There may be a higher risk of other cancers such as brain cancers.
Mutations in the gene XPV, a variant type of xeroderma pigmentosum, are characterized by sun sensitivity, elevated incidence of skin cancer, and at the cellular level, by delayed replication and hypermutability after UV-irradiation.
There is evidence evidence that the variant form of xeroderma pigmentosum (XPV) is caused by homozygous or compound heterozygous mutation in the DNA polymerase eta gene (POLH) on cytogenetic location 6p21.1 and genomic coordinates 6:43,576,185-43,620,523. The screenshot of the POLH gene 44,339 bp (base pairs) of DNA sequence length is shown BELOW. Nine (9) other genes besides POLH in the 6p21.1 cytogenetic location are listed BENEATH.
| Coordinate | Symbol | Genomic Name |
| 6:43,477,570 | TJAP1 | Tight junction-associated protein 1 |
| 6:43,511,832 | YIPF3 | YIP1 domain family, member 3 |
| 6:43,517,089 | POLR1C | Polymerase I, RNA, subunit C |
| 6:43,522,334 | XPO5 | Exportin 5 |
| 6:43,576,185 | POLH | Polymerase, DNA, eta |
| 6:43,620,494 | GTPBP2 | GTP-binding protein 2 |
| 6:43,629,540 | MAD2L1BP | MAD2L1-binding protein |
| 6:43,645,036 | RSPH9 | Radial spoke head 9 homolog |
| 6:43,671,202 | MRPS18A | Mitochondrial ribosomal protein S18A |
| 6:43,770,211 | VEGF | Vascular endothelial growth factor |
