الفهرس 
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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.
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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.
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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.
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• 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.
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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
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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).
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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.
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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.