<prompt> The following diseases have defect in DNA repair mechanism except for -Xeroderma PigmentosaFanconi syndromeHuntingtons diseaseHereditary non polyposis colon cancer  <response>: Ans. is c i.e., Huntingtons disease Several genetic disorders have defective DNA repair capability due to involvement of DNA repair enzymes. o Mutation caused by defects in DNA repair accumulate as somatic cells divide these type of mutation can cause neoplastic growth. So, all these disorders have significantly increased risk of cancer. o Inherited autosomal recessive syndromes of defective DNA repair Ataxia Telangiectasia Fanconia anemia Hereditary Nonpolyposis cancer Only Bloom syndrome Xeroderma pi gmentosum autosomal dominant o These disorders are associated with such a high level of chromosomal instability that they are known as chromosome - breakage syndrome. 