Neurons and DNA repair: neurologic involvement in xeroderma pigmentosa.

Involvement of the nervous system occurs in only some forms of xeroderma pigmentosa. A hypothesis is proposed explaining the relative vulnerability of neurons in the presence of impaired DNA repair mechanisms. A large portion of the genome is expressed in the brain, making it more susceptible to the effects of accumulated mutations. In the setting of cells which do not divide, a moderate decrease in the efficiency of the DNA repair systems may manifest in premature cell death.