A haploinsufficiency of FOXG1 identified in a boy with congenital variant of Rett syndrome.

Background: Forkhead box G1 gene (FOXG1) mutations and deletions are associated with a congenital variant of Rett syndrome (RTT). Nucleotide alterations of the coding region of FOXG1 have never caused dysmorphic features.

Patient: An 8-year-old boy with the congenital variant of RTT who showed severe psychomotor deterioration, epilepsy, acquired microcephaly, and involuntary movements including jerky movements of the upper limbs and tongue protrusion. He showed dysmorphic features including round face, anteverted nostrils, and tented upper lips. Brain magnetic resonance imaging showed hypoplasia of the frontal lobes and the rostral part of the corpus callosum. The molecular cytogenetic analysis confirmed a de novo deletion of 14q12 including FOXG1 in this patient.

Conclusion: We identified the smallest deletion of 14q12 involving FOXG1 among those previously reported. Dysmorphic facial features are a characteristic for the patients with chromosomal deletion including FOXG1. In our patient, C14orf23 is the only transcript other than FOXG1. Therefore, C14orf23 might be responsible for facial dysmorphism.