Objective: To analyze the clinical and genetic characteristics of a child featuring Xia-Gibbs syndrome.
Methods: Whole exome sequencing was carried out for the child.
Results: The patient has presented with developmental delay, hypotonia, strabismus and snoring. Cranial MRI revealed hypomyelination, while the EEGs were normal. Genetic testing revealed a de novo variant of the AHDC1 gene, namely c.730delA (p.Ile244Serfs*16), which was classified as pathogenic (PVS1+PS2+PM2). Together with 60 cases from the literature, individuals harboring a AHDC1 variant commonly have delayed motor milestones, speech delay, facial dysmorphism and hypotonia. Dysgenesis of corpus callosum is also common. In total 47 AHDC1 variants have been reported, among which truncating variants were the most common type.
Conclusion: The c.730delA (p.Ile244Serfs*16) variant of the AHDC1 gene probably underlay the Xia-Gibbs syndrome in this patient. Above finding has provided a basis for the clinical diagnosis.