Clinical characterization and genotype analysis of idiopathic mental retardation in male patients with epilepsy / 中华实用儿科临床杂志

ABSTRACT

Objective To detect genetic causes of idiopathic mental retardation/developmental delay in 20 male patients with epilepsy and to analyze their clinical characteristics of positive mutation carriers.Methods The families,consisted of the patient and his parents were recruited.Genomic DNA was extracted from peripheral blood,and candidate gene mutation screening was carried out by next-generation sequencing technology.Mutations in positive gene were verified by polymerase chain reaction(PCR) and direct sequencing.Results Three missense mutations were identified among 3 patients out of 20 cases,with a detection rate of 15％.They wereOPHN1 gene c.1996 C ＞ G,RAB39B gene c.542 C ＞ T and AFF2 gene c.427 A ＞ T,none of which had been reported before.All of these mutations were likely to be pathogenic based on gene function,evolutionary conservation,variant frequency in normal population (NHLBI Exome Sequencing Project and 1 000 Genomes),bioinformatics prediction and inheritance patterns.In addition,all 3 genes disrupted were residing on the X chromosome previously demonstrated to be associated with X-linked mental retardation(XLMR),indicating that they were probably pathogenic or might serve as one of the risk factors.Conclusions Abnormal function of genes on the X chromosomal is one of the most impotent causes of XLMR.X chromosomal gene mutation screening would be recommended for male children suffering from idiopathic mental retardation with epilepsy.