I am a Senior Research Scientist in the laboratory of
Phil Hanawalt, Biological Sciences Department, Stanford University. I have been studying the mechanisms of DNA repair in human cells for many years; my most current efforts have been concentrated on the elucidation of the biochemical basis for the human hereditary diseases, UV-sensitive syndrome (UV
SS) and Cockayne syndrome (CS). Individuals with these syndromes carry mutations in the
CSA or
CSB genes, or in a third unknown gene in some UV
SS cases; they are extremely sun-sensitive, but they are not abnormally prone to cancer. Cells from UV
SS and CS individuals are deficient in transcription-coupled repair (TCR) of "bulky" DNA adducts. The clinical hallmarks of CS include neurological/developmental abnormalities and premature aging. UV
SS cells are not sensitive to inducers of oxidative damage that are notably cytotoxic in cells from CS patients. Our findings imply that some mutations in the
CSA or
CSB genes may interfere with the TCR-dependent removal of UV-induced damage, without affecting their role in the oxidative stress response. The differential sensitivity toward oxidative stress might explain the difference between the range and severity of symptoms in CS and the mild manifestations in UV
SS patients that are limited to skin photosensitivity without precocious aging or neurodegeneration. I am currently investigating the processing of oxidative DNA lesions in cells from wild type and repair-deficient donors.