UV-sensitive syndrome-1 (UVSS1) is an autosomal recessive disorder characterized by cutaneous photosensitivity and mild freckling, without an increased risk of skin tumors. Patient cells show impaired recovery of RNA synthesis (RRS) after UV irradiation due to defective preferential repair of DNA damage in actively transcribing genes, although unscheduled DNA repair is normal. The cellular findings are consistent with a defect in transcription-coupled nucleotide excision repair (TC-NER) of UV damage (summary by Horibata et al., 2004). Genetic Heterogeneity of UV-Sensitive Syndrome See also UVSS2 (614621), caused by mutation in the ERCC8 gene (609412) on chromosome 5q12, and UVSS3 (614640), caused by mutation in the UVSSA gene (614632) on chromosome 4p16.