Thin genu of the corpus callosum points to mutation in FOXG1 in a child with acquired microcephaly, trigonocephaly, and intellectual developmental disorder: a case report and review of literature.

The FOXG1 syndrome is emerging as a relative new entity in paediatric neurology. We report a boy with acquired microcephaly, mental retardation and a thin genu of the corpus callosum. The combination of these findings led to mutation analysis of FOXG1. The patient was found to be heterozygous for a novel mutation in FOXG1, c.506dup (p.Lys170GInfsX285), which occurred de novo. This frameshift mutation disturbs the three functional domains of the FOXG1 gene. Hypo- or agenesis of the anterior corpus callosum in combination with acquired microcephaly and neurologic impairment can be an important clue for identifying patients with a mutation in FOXG1.