title: Identification of two novel mitochondrial DNA deletions induced by ionizing radiation.
abstract: OBJECTIVE
  We identify ionizing radiation-induced mitochondrial DNA (mtDNA) deletions in human lymphocytes and their distribution in normal populations.
  
  
  METHODS
  Long-range polymerase chain reactions (PCR) using two pairs of primers specific for the human mitochondrial genome were used to analyze the lymphoblastoid cell line following exposure to 10 Gy (60)Co γ-rays. Limited-condition PCR, cloning and sequencing techniques were applied to verify the mtDNA deletions detected with long-range PCR. Human peripheral blood samples were irradiated with 0, 2 and 6 Gy (60)Co γ-rays, and real-time PCR analysis was performed to validate the mtDNA deletions. In order to know the distribution of mtDNA deletions in normal population, 222 healthy Chinese adults were also investigated.
  
  
  RESULTS
  Two mtDNA deletions, a 7455-bp deletion (nt475-nt7929 in heavy strand) and a 9225-bp deletion (nt7714 -nt369 in heavy strand), occurring between two 8-bp direct repeats, were identified in lymphoblastoid cells using long-range PCR, limited-condition PCR and sequencing. These results were also observed for (60)Co γ-rays irradiated human peripheral blood cells.
  
  
  CONCLUSIONS
  Two novel mtDNA deletions, a 7455-bp deletion and a 9225-bp deletion, were induced by ionizing radiation. The rate of the mtDNA deletions within a normal population was related to the donors' age, but was independent of gender.
authors.affiliation: Department of Cardiology, Capital Medical University, Beijing, China.
authors.forename: Xiao Tao
authors.initials: XT
authors.lastname: Zhao
authors.forename: Jiang Bin
authors.initials: JB
authors.lastname: Feng
authors.forename: Yu Wen
authors.initials: YW
authors.lastname: Li
authors.forename: Qun
authors.initials: Q
authors.lastname: Luo
authors.forename: Xin Chun
authors.initials: XC
authors.lastname: Yang
authors.forename: Xue
authors.initials: X
authors.lastname: Lu
authors.forename: De Qing
authors.initials: DQ
authors.lastname: Chen
authors.forename: Qing Jie
authors.initials: QJ
authors.lastname: Liu
mesh_terms: D002460:Cell Line; D003001:Cloning, Molecular; D003037:Cobalt Radioisotopes; D004249:DNA Damage / Q000235:genetics / Q000528:radiation effects*; D004272:DNA, Mitochondrial / Q000235:genetics* / Q000528:radiation effects*; D017353:Gene Deletion; D005819:Genetic Markers; D006801:Humans; D008214:Lymphocytes / Q000528:radiation effects*; D011839:Radiation, Ionizing; D060888:Real-Time Polymerase Chain Reaction
chemical_list: D003037:Cobalt Radioisotopes; D004272:DNA, Mitochondrial; D005819:Genetic Markers