Extending the phenotype of Xia-Gibbs syndrome in a two-year-old patient with craniosynostosis with a novel de novo AHDC1 missense mutation.

Xia-Gibbs syndrome (Mental retardation, autosomal dominant 25; MRD25) [MIM 615829] is a rare autosomal dominant disease characterized by mental retardation, developmental delay, speech delay, structural brain anomalies, hypotonicity, protuberant eyes, visual problems, laryngomalacia and snoring. Since the first description in 2014, fewer than 50 patients with Xia-Gibbs syndrome have been noticed in the literature. We describe here 2 years 2 months old girl with developmental delay, brain anomalies, laryngomalacia and craniosynostosis. Whole-Exome Sequencing (WES) analyses in patient showed a heterozygous NM_001029882: c.4370 A>G; p. (Asp1457Gly) mutation in AHDC1. Craniosynostosis rarely observed in the patients described to date, and west syndrome-like EEG pattern, constipation and electrolyte imbalance observed for the first time were present in our patient. Further reports and in-vivo/in-vitro works will make possible knowing of the genetic and clinical background of this disease.