CSB (ERCC6) is a large (168 kDa), SWI/SNF family ATPase11,12 linked to a rare segmental progeria, termed Cockayne Syndrome (CS) which features neurodevelopmental defects/neurodegeneration, growth failure, photosensitivity, and a premature ageing phenotype13. Here, ERCC6 is linked to progeroid syndrome.