ERCC2 and trichothiodystrophy: Mutations in the NER pathway helicase XPD, cause -among several other inherited syndromes- a disease called Trichothiodystrophy (TTD) which is a rare, autosomal recessive DNA repair disorder presenting a wide range of characteristic features like photosensitivity, brittle hair and nails, impaired intelligence, short stature, infertility and a severely reduced lifespan.