In the case of genes within the 12p critical region implicated in macrocephaly in PKS, mutations to ABCC9 which encodes the sulfonylurea receptor (SUR) that forms ATP‐sensitive potassium channels (KATP) channels are associated with Cantú syndrome, a rare syndromic overgrowth condition which presents with macrocephaly (OMIM# 239850). Here, ABCC9 is linked to tetrasomy 12p.