<prompt> All are true about Xeroderma Pigmentosum exceptIt is autosomal dominant inheritanceDue to defective DNA repairAssociated with squamous cell carcinomaThymine dimers  <response>: A It is autosomal dominant inheritance XERODERNA PIGMENTOSUM XP Is an autosomal recessive genetic disease. The clinical syndrome includes marked sensitivity to sunlight ultraviolet with subsequent formation of multiple skin cancers and premature death. The risk of developing skin cancer is increased 1000- to 2000-fold. The inherited defect seems to involve the repair of damaged DNA, particularly thymine dimers. Cells cultured from patients with xeroderma pigmentosum exhibit low activity for the nucleotide excision-repair process. Seven complementation groups have been identified using hybrid cell analyses, so at least seven gene products XPA-XPG Are involved. Two of these XPA and XPC are involved in recognition and excision. XPB and XPD are helicases and, interestingly, are subunits of the transcription factor TFIIH. 