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Autism spectrum disorder (ASD) was previously defined as a neurodevelopmental disorder characterized by language delay, deficits in social interaction and communication, both verbal and non-verbal and restricted repetitive behaviors, interests or activities which are manifested by stereotyped, repetitive speech, motor movement or use of objects, inflexible adherence to routines, restricted interests, and hyper- and/or hypo-sensitivity to sensory input. Recently DSM-V identified just two criteria for diagnosis of ASD which are social interaction domain (including language and social communication deficits) and repetitive or restricted behaviors.
The global prevalence of ASD has markedly increased in the recent years. Autism and Developmental Disabilities Monitoring (ADDM) Network from the Centers for Disease Control and Prevention identified that 1 in 59 or 1.7% of 8-year-olds was diagnosed as ASD. In Egypt, the median rate is 62 cases per 10,000 individuals with average rate 4.3: 1 male to female ratio. Also an Egyptian screening study for ASD flagged a considerable result which was (23.8%) of Egyptian toddlers were suspected to have ASD.
ASD etiology is still a confusing question without a definite answer. It has long been presumed that there is a common cause at the genetic, cognitive, and neural levels for autism’s characteristic symptoms. During last decades, considerable advances have been made in the clinical epidemiological researches of autism and the new advances have proved important clues about the etiologies and mechanisms of this disorder.
Different underlying mechanisms have been postulated to explain the etiology ASD symptoms. Genetic and environmental factors are highly correlated to ASD. Recent research proved variety of structural variations and gene mutations with subsequent behavioral, cognitive and neurological disturbance among ASD cases.
Also, it was proved that genetic disturbances are highly distressing the metabolic system leading to various metabolic disorders with different comorbidities with ASD. The prevalence of inherited metabolic disorders in ASD cases reached 30% which is hundreds times higher than their presence in the normal populations.
The underlying mechanism of this accordance depends on main4 mechanism which are immunologic/inflammation, oxidative stress, environmental toxicants, and mitochondrial abnormalities.
Regarding the diagnosis of ASD, however symptoms start to appear early in the 2nd year, most of cases are lately discovered. from this point, our study aimed to early screening for the Autism Spectrum Disorder among one of the high risk groups for ASD, infants diagnosed of metabolic disorders.
It was done through using the validated Arabic version of the screening test (Modified Checklist for Autism, Revised and Follow-up). The test was applied on 100 children diagnosed as having metabolic disorders with age range of (16-30) months excluding children with visual or hearing impairment from the study.
The results showed that 20 % of the studied cases were at low risk for ASD, 58% were at medium risk and 22% were at high risk. But only 16% were true ASD and 84% were non-ASD cases but may have any other developmental concern other than ASD. The mitochondrial disorder had the highest percentage of ASD cases.
We have to conclude that Children with various metabolic disorders are considered a high risk group for different developmental concerns; one of the most important is ASD. So, screening for ASD is of a great significance for this suspicious group for early detection of ASD cases and providing better prognosis through starting therapy as early as possible.