The Clinical And Genetic Etiology Study Of Infantile Spasms

Part One:The Clinical Study of 195 infantile spasmsBackground:Infantile spasms is the most common infancy epileptic encephalopathy, with unclear etiology, lack of targeted therapies and unfavorable prognosis. Nowadays, the diagnosis of infantile spasms is mainly based on the clinical feature, and the standard etiological and molecular diagnosis is still not founded. The aim of this study is to set the procedure to analyze the clinical feature of infantile spasm and follow up the prognosis.Method:The retrospective data analysis and cohort study were used to analyze the clinical documents of 195 cases. All the cases were analyzed in the fields of clinical history,clinical features, physical and neurological examinations, imaging and metabolic tests, routine genetic tests to make the etiological diagnosis. Having recorded the therapies simultaneously, the follow-ups for the seizure, intellectual development and the complication were engaged, and the disease course more than 2 years were selected into the statistical group. The cases with definite etiology being excluded and the doubt of having genetic background were undertaken genetic research in the second parts.Result:Totally, there were 195 Chinese children with infantile spasms included in this study, all is of Han nationality, including 120 male and 75 female (M:F 1.6:1). The average onset age was 5.85±4.39 months,177 of 195 cases were recorded having hypsarrhythmia at least once on EEG. There were 130 (67%) cases of symptomatic IS and 75 (33%) cases of cryptogenic IS. In the symptomatic IS, there includes 82 cases with birth defect(15 with tuberous sclerosis,44 with intrauterine or postnatal growth retardation,2 with Down’s syndrome,12 with other error birth defect and 48 cases with postnatal brain injury. The 147 cases with birth defect and with cryptogenic etiologies were molecularly suspected to have genetic background. All children were treated by combined multiple AEDs, the sodium valproate was the most common used AED in 170 patients in the fist six months of treatment.50 patients got seizure free more than one year, in which,17 were treated with valproate combined with topiramate.135 patients were with the disease course more than two years,94.8% showed poor prognosis.38 IS developed into refractory seizure,128 patients showed moderate to severe intellectual disability,11 patients showed autism feature, and 2 was confirmed by ADOS, and 2 patients were died.Conclusion:Infantile spasms is a kind of severe EE, we still face huge challenge to cure this disease, and the overall prognosis was unfavourable.The 147 cases with birth defect and cryptogenic etiologies were molecularly suspected to have genetic background. patients showed moderate to severe intellectual disability,11 patients showed autism feature, and 2 was confirmed by ADOS, and 2 patients were died.Part Two:The Genetic Etiology Study of Infantile SpasmsBackground:Infantile spasm (IS) is a specific type of epileptic encephalopathy associated with severe developmental disabilities. Genetic factors are strongly implicated in IS, however, the exact genetic etiology remains unknown in the majority of cases. Rare single gene mutations or copy number variants (CNVs) have been implicated in children IS in Western countries. The objective of this study was to dissect the genetic etiology role of copy number variations and targeted gene panel sequencing in Chinese children with infantile spasms.Methods:The Agilent Human Genome CGH microarray 180K for genome-wide was used to detect of CNVs. Real-time qPCR was used to validate the CNVs. We performed genomic and medical annotations for individual CNVs to determine the pathogenicity of CNVs related to IS. These CNVs were divided into four groups, ① the known reported IS related pathogenic CNV; ②the known pathogenic CNV first reported in IS patients;③the clinical meaning still not clear④ polymorphism CNV variants. The patients detected no pathogenic CNVs will be sequenced by 407 epilepsy targeted gene panel. The targeted genes were captured using the NimbleGen platform and sequenced by Hiseq 2000. The data were analyzed according to standard bio-informatics analysis, functionality and conservation prediction of SNPs, as well as the analysis based on family samples. The cutoff value to define the rare mutation was 0.05.Results:We report herein the first genome-wide CNV analysis in 47 children with IS, detecting a total of 14 CNVs. Four CNVs (4/47=8.5%) (1q21.1 gain; 1q44,2q31.1, and 17p13 loss) are considered to be pathogenic. The CNV lost at 17p13.3 contains PAFAH1B1 (LIS1), a causative gene for lissencephaly. Although the CNVs at 1q21.1,1q44, and 2q23.1 have been previously implicated in a wide spectrum of clinical features including autism spectrum disorders (ASD) and generalized seizure, our study is the first report identifying them in individuals with a primary diagnosis of IS. The CNV loss in the lq44 region contains HNRNPU, a strong candidate gene recently suggested in IS by the whole exome sequencing of children with IS. The CNV loss at 2q23.1 includes MBD5, a methyl-DNA binding protein that is a causative gene of ASD and a candidate gene for epileptic encephalopathy. We also report a distinct clinical presentation of IS, microcephaly, intellectual disability, and absent hallux in a case with the 2q23.1 deletion. Totally,63 proband were sequenced. The average 357 ±24 rare variant was detected. The 30 trios were analyzed. The detect rate was 6.3%. Among these, except CDKL5, STXBP1, TSC2, SLC2A1, the known IS related gene, we also concerned ARHGEF9, MEF2C, ALDH7A1, RYR3, CACNA2D1, CACNA1I participated in. Besides, there were some other variants, the significance still unclear and need further study about their functions.Conclusion:_Our findings strongly indicate that CNVs play the role in infantile spasms and expand the clinical spectrum associate with 2q23.1 deletion. Particularly, our study first reported the HNRNPU and MBD5 genes in Chinese children with IS. Our study also supports that the molecular mechanisms of infantile spasm appear conserved among different ethnic backgrounds.. Using the NGS containing 407 epilepsy related genes, we detected CDKL5, STXBP1, TSC2, SLC2A1 the known IS related gene, also some other gene including ARHGEF9, MEF2C, ALDH7A1, RYR3, CACNA2D1, CACNAII may involved in. 1q44, and 2q23.1 have been previously implicated in a wide spectrum of clinical features including autism spectrum disorders (ASD) and generalized seizure, our study is the first report identifying them in individuals with a primary diagnosis of IS. The CNV loss in the lq44 region contains HNRNPU, a strong candidate gene recently suggested in IS by the whole exome sequencing of children with IS. The CNV loss at 2q23.1 includes MBD5, a methyl-DNA binding protein that is a causative gene of ASD and a candidate gene for epileptic encephalopathy. We also report a distinct clinical presentation of IS, microcephaly, intellectual disability, and absent hallux in a case with the 2q23.1 deletion. Totally,63 proband were sequenced. The average 357 ±24 rare variant was detected. The 30 trios were analyzed. The detect rate was 6.3%. Among these, except CDKL5, STXBP1, TSC2, SLC2A1, the known IS related gene, we also concerned ARHGEF9, MEF2C, ALDH7A1, RYR3, CACNA2D1, CACNA1I participated in.