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Abstract Epilepsy is one of the most serious brain disorders. It affects approximately 50 million people worldwide. In fact, 1 to 2% of the population risk to develop an epileptic seizure making the development of a treatment for this disease a scientifical and medical challenge. In spite of the expansion of a large variety of antiepileptic drugs (AEDs), approximately one third of the patients remain refractory to treatment and affecting their daily social activity, life quality and well-being. Epilepsy drug-resistance may be due to complex mechanisms not understood up to this time. This resistance depends on many aspects including; (i) clinical factors: age, age at seizure onset, syndrome and seizures types, etiology of epilepsy, medical history, (ii) genetic factors affecting pharmaco-kinetics or pharmacodynamics of AEDs, (iii) or both. The main theory suggests that the dysfunction of the Pglycoprotein (P-gp) an efflux-pump protein responsible of the transport and the elimination of various AEDs at the blood-brain barrier (BBB), changes the treatment response leading to a refractory epilepsy. As a matter of fact, abnormal structure of the target protein or multidrug-protein transporters dysfunction may cause insufficient AEDs levels in the brain which leads to AEDs resistance. The ABCB1 gene, which encodes for the P-gp, is located in the chromosome 7p21 of the human genome and is composed of 29 exons. Summary 126 More than 50 single nucleotide polymorphisms (SNPs) have been described in this gene, the most studied genetic variants in ABCB1 gene are: C1236T (rs1128503) in exon 12, G2677T (rs2032582) in exon 21 and C3435T (rs1045642) in exon 26, due to their association with different expressions and functions of this gene. In fact, the C3435T is often referred to as a critical polymorphism in AEDs resistance. The drug-resistant patients were more likely to have the C3435T CC genotype than the TT and this genotype was correlated with high intestinal P-gp expression. Furthermore, other studies suggested that this genotype could be correlated with high P-gp expression in brain tissue which causes AEDs concentration reduction in the BBB. Even though association between epilepsy drug-resistance and ABCB1 polymorphisms was confirmed by several studies. The goal of the work is to investigate the possible association of two ABCB1 gene polymorphisms (C3435T and C1236T) with the development of RE and AED response in a sample of Egyptian epileptic patients. The current study was a prospective case–control study that was conducted on 50 of Egyptian children with controlled epilepsy, 50 of Egyptian children with refractory epilepsy and 50 apparently healthy children age, sex and socioeconomic status matched as control group. All diagnosed cases will be based on clinical examination and EEG changes. All epileptic children were recruited from the Pediatrics Department and outpatient clinic Menoufia University Hospital during period from April, 2020 to May, 2021. Summary 127 II. Studied groups: group (1) patient group: which subdivided into: -Group(A): included 50 Egyptian children with refractory epilepsy. All of them meeting criteria of refractoriness. -group (B): included 50 Egyptian children with controlled epilepsy. Inclusion criteria: Age (1-16 years) Patient with idiopathic epilepsy. Exclusion criteria: Patient with syndromic epilepsy. Patient with organic brain lesion. group (2) control group: included 50 apparently healthy children age, sex and socioeconomic status matched as control group. Ethical considerations: The study was approved by the ethical committee of the Faculty of Medicine, Menoufia University with IRB NO PEDI27 3/2021. All children included in the study were subjected to the following: • Full history taking. • Complete general and clinical examination. • Laboratory investigations: Serum total calcium, ALT, AST and Ionized calcium. • Radiology investigations: EEG and MRI Brain. Summary 128 • Molecular assays of two SNPs in ABCB1 gene using conventional PCR with specific sets of primers for C3435T and C1236T polymorphisms. Results of the current study could be summarized as follow: No significant difference found between the studied groups regarding their socio demographic data (P value >0.05). Age of onset was slightly higher in responsive group than refractory group but not reached significant level (P value 0.077). All responsive group used only one drug for treatment while refractory group used two types or more and the difference between the two groups was statistically significant (P value 0.001). No significant difference between first and follow up attack in refractory group (P value >0.05), while there was significant difference between first and follow up attack in responsive group (P value 0.001). Children with refractory epilepsy had significantly lower weight and BMI than responsive and control groups (P value <0.05), while no significant difference in height found between the studied groups (P value > 0.05). No significant difference found in total and ionized calcium level and AST level between the studied groups (P value >0.05). ALT level was significantly higher in refractory and responsive groups than control group (P value 0.001). Milestones, mentality, speech and motor system were affected in 36% (18 patients) in refractory group. Summary 129 Tanner stage revealed delayed puberty in 8 % of refractory group versus 0% in control group which was statistically significant (p 0.041). No significant difference in initial EEG finding between refractory and responsive groups (P value >0.05), while there was significant improvement in follow up EGG in responsive group (P value 0.001). Regarding to C3435T gene polymorphism there was significant difference between haplotype TC and CC among refractory group when compared with control group (P value = 0.005), also there was significant difference between TC and CC variants among both refractory and responsive group. While no significant difference in haplotype TT among the studied groups, C allele had a significant difference between refractory and control group, also between refractory and responsive group (P value 0.002, 0.032 respectively). C1236T gene polymorphism did not show significant difference between haplotype TC, CC and TT among the studied groups. Regarding to C allele there was no significant difference among the studied groups. No significant difference between the three C3435T gene variants TT, TC and CC regarding all demographic data in refractory group (P value <0.05), while in responsive group CC haplotype, more associated with increase age range (6-15) years, more in rural area (78%), also related to low socioeconomic level (71.4%) and lastly related to positive consanguinity (78.6%). There was significant relation between C3435T gene polymorphism and disease duration in refractory epileptic Summary 130 children with long duration of illness in CC variant (P value = 0.043). There was significant relation between CC haplotype of C3435T gene polymorphism with age of onset, first attack of epilepsy mostly 1st attack was GTC, frequency (1–5 times weekly) and fever was the higher aggravating factors in responsive epileptic children (P value <0.05) while, no significant difference between first and follow up attack in refractory group (P value >0.05). No significant relation between C3435T gene polymorphism and CNS examination among the studied patients (P value > 0.05). Also, no significant relation between C3435T gene polymorphism and radiological investigations among the studied patients (P value >0.05). There was no significant relation between C1236T gene polymorphism and socio demographic data of refractory epileptic patients (P value >0.05). In responsive epileptic group there was significant relation between C1236T gene polymorphism and residence (TT associated with urban residence P value 0.001), 100 % of CC with low socioeconomic level of patients (P value <0.05). In responsive epileptic group there was significant relation between C1236T gene polymorphism and duration of disease less duration in CC, all patients with C allele suffered from GTC as a first attack with 1–5-time frequency /week, also there is significant relation between C1236T gene polymorphism and fever as an aggravating factor (P value <0.05). Summary 131 There was significant relation between C1236T gene polymorphism and aggravating factors in refractory epileptic patients (P value <0.05). No significant relation between C1236T gene polymorphism and CNS examination among the studied epileptic patients (P value >0.05) also, had no significant relation with radiological investigations among the studied epileptic patients (P value >0.05), in addition to MRI brain was not significant. C3435T gene polymorphism is independent predictor for refractory epilepsy. Presence of C allele had about three folds increases risk for refractory epilepsy. Conclusions C3435T CC variant and C allele were found to be statistically significant in refractory epileptic patient when compared with responsive group of patients and control group. The three C1236T genotypes and alleles did not show any difference between the three groups refractory, responsive and control. C3435T polymorphism is undependable predictor for refractory epilepsy and allele C has about 3 folds increase risk of refractoriness and large duration of illness. There is no significant relation between C3435T polymorphism and EEG changes whether initial or follow up EEG. Summary 132 Recommendations Further genetic study with large scale and multicentric study to validate our result. Long term follow up to patients with C3435T mainly with C allele with good genetic counselling. |