Carcinogenesis: DNA repair genes

1. General

   1. Ability of normal cells to repair DNA damage and prevent mutations in genes that regulate cell growth and apoptosis

   2. Also repair alterations from errors that occur spontaneously

   3. People who inherit mutations of DNA repair proteins are at greater risk for developing cancer

2. Hereditary nonpolyposis colon carcinoma (HNPCC)

   1. Familial carcinoma of the colon, not arising from polyp

   2. Defect in genes involved in DNA mismatch repair

   3. Mutations in at least 4 mismatch repair genes have been identified

3. Xerodoma pigmentosa (XP)

   1. Develop skin carcinomas

   2. Defective DNA repair of UV light induced pyrimidine dimmers

      1. normally repaired by nucleotide excision repair system

      2. several proteins/genes involved

      3. inherited loss of any one can cause XP

4. Autosomal recessive disorders

   1. Bloom’s syndrome and ataxia telangiectasia

      1. hypersensitivity to ionizing radiation

   2. Fanconi’s anemia

      1. hypersensitivity due to DNA cross-linking agents such as nitrogen mustard (chemotherapy agent)

      2. radiation induced DNA damage

Category: Pathology Notes