DNA Repair Dysfunction and Neurodegeneration: Lessons From Rare Pediatric Disorders

Progressive length-dependent polyneuropathy in xeroderma pigmentosum group A

BACKGROUND

In this study, we aimed to investigate the progression of peripheral nervous system involvement in xeroderma pigmentosum group A (XP-A).

METHODS

We performed nerve conduction studies in 17 genetically confirmed XP-A patients and conducted follow-ups. Of these patients we also analyzed gray matter volume (GMV) using brain MRI and assessed the severity score of clinical and skin manifestation.

RESULTS

We found significant reduction in the motor and sensory nerve action potential amplitude and mild reduction in conduction velocity. These findings were predominant in sensory nerves and the lower limbs, were observed since early childhood, and gradually deteriorated with age.

CONCLUSIONS

The electrophysiological characteristics of XP-A patients are consistent with length-dependent axonal polyneuropathy and there is progressive deterioration from early childhood.

Xeroderma Pigmentosum

Xeroderma pigmentosum (XP) is a rare disorder of defective UV-radiation induced damage repair that is characterized by photosensitivity with easy skin burning following minimal sun exposure, early freckling and development of lentiginous pigmentation along with other features of poikiloderma and a propensity for developing skin cancer at an early age. In this short review, the clinical, pathological, genetic and molecular aspects of XP are reviewed in the current literature. XP encompasses a spectrum of disease that overlaps with other diseases of DNA repair systems. In addition to cutaneous complications, patients are susceptible to eye conditions, neurodegenerative processes, central nervous system tumors and other tumors as a result of UV radiation exposure and its byproducts. Patients with XP frequently experience a shorter life span due to skin cancer and neurodegenerative sequelae, but aggressive preventative measures to minimize UV radiation exposure and damage can improve the course of disease and prolong life. The disease has served as a model for photoaging and UV radiation-induced cancer and has led to a better understanding of cell processes that prevent development of these disease features in normal individuals.