A bi‐allelic frameshift mutation in KCTD3 (c.1036_1073del, p.P346Tfs*4) was first identified in one family by whole exon sequencing of 143 multiplex families with neurocognitive disorders.88 This same KCTD3 mutation was later reported in a 2.5‐year‐old patient.89 Homozygous KCTD3 mutations were identified in three additional families, one harboring the same frameshift mutation (c.1036_1073del, p.P346Tfs*4), and the other two harboring a missense mutation (c.166C > T, p.Arg56*).90KCTD3 patients exhibit global developmental delay, seizures, and cerebellar hypoplasia.88, 90. The gene discussed is KCTD3; the disease is Cerebellar hypoplasia.