Cockayne syndromes can result from mutations in either the excision repair cross-complementation group 6 (ERCC6) gene or the ERCC8 gene involved in repairing damaged DNA, but early reports found no obvious genotype-phenotype correlations for mutations in either ERCC8 or ERCC6, suggesting that the clinical variability within the CS spectrum may not be accounted for gene mutation alone [112]. Here, ERCC6 is linked to Cockayne syndrome.