Remarkably, mutations within the TFIIEβ subunit recently have recently been associated with trichothiodystrophy (TTD), an autosomal recessive developmental disorder mainly related to TFIIH mutations (mostly in ERCC2/XPD gene and few cases in ERCC3/XPB or GFT2H5/p8/TTD-A genes) and characterized by brittle hairs with alternating dark and light (“Tiger tail”) banding with polarized microscopy and low content of sulfur-containing amino acids25,26. Here, ERCC2 is linked to trichothiodystrophy.