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Abstract
Autism is a permanent developmental disorder characterized by marked deficits in communication and special interaction skills, language impairment, and abnormal behavior. After decades of research the cause of autism is still unknown. The etiology of autism is heterogeneous, comprised of genetic and environmental factors. It is possible that one case may be caused by one factor, another case by different factors, and still another by multiple factors.There is not a clear pathway of mechanisms directed towards a simple pathogenesis and an established link to autism on the symptomatic level; there are however several important theories like neural connectivity, Neural migration, excitatory-inhibitory neural activity, dendritic morphology, neuroimmune calcium signalling and mirror Neuron) which appear to offer an explanation to how autism develops. It seems probable that autism’s neurodevelopmental defect is multi-domain in origin (rather than a single anomaly) and is hence distributed across numerous levels of study (Genetic, immunopathogenic, etc).Early brain overgrowth occurs during development-ally critical years that are normally characterized by development of language, social, emotion, and attention skills for the typically developing toddler, but strikingly deviant development for the infant and toddler with autism.BDNF is a small dimeric and a member of the neurotrophic factor family, is expressed widely throughout the mammalian brain. It plays a key role in regulating neuronal survival, in the formation of functional synapse, in the plasticity of synaptic connections, and in regulating differentiation and maintenance of phenotype in mature neurons. BDNF both enhances quantal synaptic transmission as well as promotes dendritic spine formation.There have been great controversies in studying relationship between BDNF and autism.Since autism is a neurodevelopmental disorder that begins in childhood and BDNF is important in neuro-development, BDNF is of suggestive potential usefulness as sub-diagnostic biological marker of autism and that the investigation of this role may lead autism investigators in a new direction of research and the development of effective treatment modalities.This is case control , cross sectional study , aimed to assess levels of serum BDNF using enzyme – linked immunosorbent assay (ELISA) qualification methods in a sample of autistic children and correlate of these levels with different autistic features (severity of autism).The study included two groups, Patient group of 20 newly diagnosed cases with autism and control group of 20 non autistic, developmentally normal children, matched for age and gender.In the current study, these was no significant difference between serum level of BDNF in the autistic group compared to the age and gender matched normally developing children of the control group ,there was significant increase in head circumference in patient group compared to control group .Patients were divided into two groups, high BDNF group and low BDNF group according to the mean BDNF control, comparison between the two groups showed that there was statistical difference significance between the mean age of patients with low BDNF (8.41yrs) compared to mean age patients with higher BDNF levels (5.12yrs).There was statistically significant difference between the two groups regarding head circumference, it was significantly increased in high BDNF group, and our results showed that there is a positive correlation between BDNF concentrations and head circumference in patients with autism.There was no statistically significant difference regarding IQ between the two subgroups, also there was no significant difference regarding the mean CARS between them.Our results showed that in patient group, there was significant negative correlation between BDNF and age, there was no significant correlation between BDNF and CARS, no significant correlation between BDNF and IQ.Our study concluded that BDNF is an important factor but not the only potential biological marker of autism.Therefore, further examination is needed to confirm our results using a larger number of patients of different age, compared to age – matched control subjects.