De novo mutations in ASXL family members are associated with various developmental defects: ASXL1 mutations are linked to BOS, ASXL2 mutations to Shashi–Pena syndrome (SPS), and ASXL3 mutations to BRS [10,62,63,64,65,66]. This evidence concerns the gene ASXL3 and Buschke-Ollendorff syndrome.