Repair efficiency and PUVA therapeutic response variation in patients with vitiligo.

Vitiligo is an acquired depigmentation disorder affecting 0.1% to >8.8% in Indian population. Psoralen and ultraviolet A radiation (PUVA) is a gold standard treatment for vitiligo, however, response is still empirical. In order to investigate whether drug response variation is influenced by the repair ability of PUVA treated vitiligo subjects, single cell gel electrophoresis (SCGE) for genotoxicity and serum malonaldehyde (MDA) for cytotoxicity were performed on 107 subjects (77 cases and 30 healthy controls) in South Indian population. In vitro repair ability was assessed by considering the residual damage. A significant difference was observed between the patients and controls with regard to their mean values of DNA damage and MDA levels (p<0.05). On categorization to fast and slow responders based on the time of response, patients exhibited a significant deviation in residual DNA damage, suggestive of variation with respect to DNA repair efficiency (p<0.05). This is the first study to our knowledge with respect to PUVA drug response variation in vitiligo in relation to DNA repair. Large systematic studies on DNA repair may help in a better understanding of the mechanisms involved in the PUVA drug response variation.