Patient present with skin bullae on the sun exposure. The defect is of: (A) Sugar changes, (B) DNA methylation, (C) Thymidine dimers, (D) Trinucleotide repeats
Answer is C. A pair of abnormally chemically bonded adjacent thymine bases in DNA, resulting from damage by ultra-violet irradiation. The cellular processes that repair this lesion often make errors that create mutations.