Abstract: Objective To report a case of X-linked intellectual disability and explore the relationship between its clinical phenotype and genotype. Method　The clinical data of a male child with epilepsy and intellectual disability were retrospectively analyzed. The whole exome capture sequencing was used to analyze the gene mutation. Results　The male child had delayed development in the 4th month of age. Seizure was noted in the 5th months of age. Mental retardation was found when he was 4-years old. The tested visual acuity suggested high myopia at 7 years old. Scalp EEG recording indicated epileptic discharge. Mega cisterna magna was observed on brain MRI. The total intelligence quotient was 49. Social adaptive quotient was assessed as moderately abnormal. Sequence analysis demonstrated a novel frameshift mutation c.1641delA (p.K547fs*5) in exon 19 of OPHN1 gene in the patient. The family co-separation verification found that the healthy mother carried the variation. According to the ACMG guidelines, the mutation was classified as pathogenic. The anti-epilepsy drugs sodium valproate and lamotrigine were effective. Conclusions　The OPHN1 gene mutation c.1641delA(p.K547fs*5) may be the cause of X-linked intellectual disability. The clinical phenotypes of the patient included epilepsy, moderate intellectual disability, high myopia and mega cisterna magna on brain MRI.

Key words: OPHN1 gene;　X -linked intellectual disability;　epilepsy;　high myopia