A 6 year old boy is brought to GP due to two black and brown, irregularly shaped moles on back of his neck. He has a history of heightened reaction to sunlight, with skin blistering occuring after exposure to the sun. His skin in sun-exposed areas is dry, has areas of mottled hyperpigmentation and hypopigmentation and telangiectasias. His mother says bright light bothers him. Opthalmologic examination shows keratitis, conjunctivitis and opacities in lens of both eyes. A year ago a squamous cell carcinoma was removed from hsi forehead. 1. What is the likely diagnosis and why? 2. The protein most likely defective in this boy leads to an accumulation of which type of DNA mutation?

Connective tissue is the most abundant type of tissue in the body. It serves to connect and support other tissues and also has regulatory and immunologic functions. Connective tissue consists of cells, mainly fibroblasts, and an extracellular matrix (ECM).