[Clinical analysis of early-onset infantile epileptic encephalopathy associated with synonymous variant of the ARHGEF9 gene].

Objective: To explore the clinical characteristics of a child with early-onset infantile epileptic encephalopathy type 8 associated with synonymous variant of ARHGEF9 gene.

Methods: Clinical data of the patient was summarized. The child and his parents were subjected to trio-whole exome sequencing.

Results: The child has presented with global developmental delay, epilepsy, impulsive behavior, hypersensitivity to sound, and mental retardation. He was found to harbor a de novo synonymous variant c.741C>T (p.Cys247Cys) of the ARHGEF9 gene. RNA splicing analysis confirmed that the variant has led to abnormal splicing of exon 5, resulting in a 55-bp deletion.

Conclusion: The clinical features of ARHGEF9 gene-related early-onset infantile epileptic encephalopathy type 8 includes mental and motor developmental delay, epilepsy, auditory allergy, and hyperactivity impulsivity. For synonymous variant, in vitro study and transcriptional experiment may be carried out to evaluate its functional and splicing effect. Above finding has enriched the phenotypic and genotypic spectrum of the ARHGEF9 gene.