Which are the causes of Xeroderma Pigmentosum?

Xeroderma Pigmentosum is caused by inherited mutations in genes responsible for the nucleotide excision repair (NER) pathway, which prevents the body from repairing DNA damage caused by ultraviolet (UV) light.

The Genetic Basis of Xeroderma Pigmentosum

To understand Xeroderma Pigmentosum, imagine your DNA as a library of instruction manuals for your cells. Every day, exposure to sunlight causes "typos" in these manuals. In healthy individuals, specialized proteins act like proofreaders, constantly scanning for and fixing these typos. In people with Xeroderma Pigmentosum, the genes that encode these proofreading proteins are mutated. Specifically, variants in one of eight genes (XPA through XPG, and POLH) disrupt the NER pathway. Because this is an autosomal recessive condition, a child must inherit one mutated copy of the gene from each parent to develop the disease.

Environmental Triggers and Mechanisms

While the genetic mutation is the root cause, ultraviolet radiation from the sun is the essential environmental trigger. Without the ability to repair UV-induced DNA lesions, these "typos" accumulate rapidly, leading to cell death or, more dangerously, the uncontrolled cell growth that results in skin cancers. It is important to distinguish between the cause (the genetic defect) and the risk factor (exposure to sunlight). The genetic defect is present from conception, but the clinical manifestations of Xeroderma Pigmentosum are directly accelerated by environmental light exposure.

Current Research and Etiology

The etiology of Xeroderma Pigmentosum is well-understood at a molecular level; however, researchers are currently investigating why the severity of symptoms varies so greatly between patients with the same genetic mutation. Current studies are focusing on gene therapy and mRNA-based treatments aimed at restoring DNA repair functions in skin cells. By better understanding how these specific mutations affect cellular metabolism and genomic stability, we hope to develop more targeted protective therapies for the Xeroderma Pigmentosum community.

Medical Disclaimer: This information is for educational purposes only and does not constitute medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions regarding a medical condition.

References

• NIH Genetic and Rare Diseases Information Center (GARD)


• Orphanet: The portal for rare diseases and orphan drugs


• Online Mendelian Inheritance in Man (OMIM)