AHDC1 and obstructive sleep apnea syndrome: Additionally, the first reports of Xia-Gibbs syndrome, caused by a heterozygous mutation in the AHDC1 gene, involved children with corpus callosum hypoplasia, intellectual disability, delayed development, failure to thrive, hypotonia, esotropia, dysmorphic features, including low-set ears and flat nasal bridge, and obstructive sleep apnea [12].