Loss-of-function de novo mutations in theSETD5gene, encoding a putative methyltransferase, are an important cause of moderate/severe intellectual disability as evidenced by the results of sequencing large patient cohorts. We present the first familial case of aSETD5mutation contributing to a phenotype of congenital heart defects and dysmorphic features, with variable expression, in two siblings and their father. Interestingly, the father demonstrated only mild intellectual impairment. Family based exome sequencing combined to careful parental phenotyping may reveal a more complex clinical picture in newly recognized syndromes. © 2016 Wiley Periodicals, Inc.