ERCC5 and progeroid syndrome: To determine the relevance of our findings for human diseases, we investigated segmental progeroid syndromes caused by GG-NER/TCR defects, specifically in primary fibroblasts39,39 from a patient (96RD235) suffering profound GG-NER/TCR defects due to a very severe mutation caused by a deoxycytidine deletion in the codon coding for the Arg45 in the NER gene XPG, that causes a C-terminal truncation in the protein39–41.