ATM and rheumatoid arthritis: Most DSBs are repaired by DNA damage response (DDR) pathways but are lethal if unrepaired.15 16 Genetic alterations in DDR genes can increase radiosensitivity as seen in several genetic syndromes, and they also play a role in the pathogenesis of RA.12 17 Polymorphisms in the many genes implicated in RA could result in a radiosensitive, immunodeficient phenotype, seen in previous literature with ATM.