<prompt> All of the following are true about syndrome with microsatellite instability, except:DNA repair defectsAutosomal dominantIncreased risk of malignancyMay be associated with immunodeficiency  <response>: Microsatellites are tandem repeats of one to six nucleotides found throughout the genome. In normal people the length of these microsatellites remains constant. Hereditary nonpolyposis colon cancer HNPCC syndrome also known as Lynch syndrome is an autosomal dominant disorder with defective mismatch repair genes. The most commonly affected genes are MSH2 and MLH1, each accounting for approximately 30 of HNPCC syndrome. If mismatch repair is defective, microsatellites are unstable microsatellite instability and increase or decrease in length, creating mutated alleles. These mutations increase risk of malignancy such as colon cancer. Not associated with immunodeficiency. Ataxia telangiectasia syndrome ATM gene is characterized by neurodegeneration, ataxia, immunodeficiency, hypersensitivity to radiation and predisposition to cancer. 