RESUMEN
In the present study, micronuclei [MN] were determined in different sites in the oral cavity of 4 XP patients in order to determine whether a relationship exists between exposure to ultraviolet light and the level of chromosomal breakage. These sites were the right and left buccal mucosa, the dorsal tip of the tongue and the palate. Six controls matched for age and sex were examined concurrently. Beta-carotene were given to the four patients in a dose of 180 mg/week for 3 months. They were followed up every four weeks by taking buccal smear samples from the same sites order to detect any change in the frequency of MN. Before treatment, an unequal distribution of the frequency of MJN was found in the different samples sites of the oral cavity in XP patients with the greatest elevation in frequencies among cells collected from the tip of the tongue [0.76 +/- 0.15]. In constant, the MN frequency did not vary in samples from different sites obtained from the controls. The frequencies of MN were higher in XP patients than in controls for all sites expect the palate where technical difficulties were encountered