For this example, we assumed that we were trying to generate evidence to classify variants in ERCC6. About 70% of individuals with Cockayne syndrome have pathogenic variants in ERCC6 and 30% in ERCC8. 16,17 For simplicity, we set aside phenotype variations in Cockayne syndrome and genotype-phenotype correlations with these two genes. This evidence concerns the gene ERCC6 and Cockayne syndrome.