TY - JOUR T1 - A novel splice variant of the DNA-PKcs gene is associated with clinical and cellular radiosensitvity in a xeroderma pigmentosum patient. JF - Journal of Medical Genetics JO - J Med Genet DO - 10.1136/jmg.2009.068866 SP - jmg.2009.068866 AU - Fatemeh Abbaszadeh AU - Peter H Clingen AU - Colin F Arlett AU - Piers N Plowman AU - Emma C Bourton AU - Matthew Themis AU - Evgeny M Makarov AU - Robert F Newbold AU - Michael H Green AU - Christopher N Parris Y1 - 2009/01/01 UR - http://jmg.bmj.com/content/early/2009/10/01/jmg.2009.068866.abstract N2 - Background: Radiotherapy-induced DNA double strand breaks (DSB) are critical cytotoxic lesions. Inherited defects in DSB DNA repair pathways lead to hypersensitivity to ionising radiation, immunodeficiency and increased cancer incidence. A patient with xeroderma pigmentosum complementation group C, with a scalp angiosarcoma exhibited dramatic clinical radiosensitivity following radiotherapy, resulting in death. A fibroblast cell line from non-affected skin (XP14BRneo17) was hypersensitive to ionising radiation and defective in DNA double strand break repair. Aim: To determine the genetic defect causing cellular radiation hypersensitivity in XP14BRneo17 cells. Methods: Functional genetic complementation whereby copies of human chromosomes containing genes involved in DNA DSB repair (chromosomes 2, 5, 8 10, 13 and 22) were individually transferred to XP14BRneo17 cells in an attempt to correct the radiation hypersensitivity. Clonogenic survival assays and γ-H2AX immunofluorescence were conducted to measure radiation sensitivity and repair of DNA DSBs. DNA sequencing of defective DNA repair genes was performed. Results: Transfer of chromosome 8 (location of DNA-PKcs gene), and transfection of a mammalian expression construct containing the DNA-PKcs cDNA restored normal ionising radiation sensitivity and repair of DNA DSBs in XP14BRneo17 cells. DNA sequencing of the DNA-PKcs coding region revealed a 249 bp deletion (between base pairs 3656-3904) encompassing exon 31 of the gene. Conclusion: We provide evidence of a novel splice variant of the DNA-PKcs gene associated with radiosensitivity in a xeroderma pigmentosum patient and report the first double mutant in distinct DNA repair pathways being consistent with viability. ER -