Hypoplasia of the fifth fingers with dysmorphism and intellectual disability can be observed in mosaic trisomy 9,20 deafness-onychodystrophy–osteodystrophy–mental retardation syndrome21 and phenytoin embryopathy.22 There is overlap between mild forms of Cornelia de Lange syndrome and individuals with SOX11 mutations.23 It is important to note that none of our cohort had a clinical diagnosis of CSS prior to CGH or exome sequencing being performed. Here, SOX11 is linked to Intellectual disability.