ABSTRACT
One of the settled facts in the etiology of autism is that genetic and environmental factors play a role in its occurrence. However, the recent dramatic increase in autism prevalence world, suggests other factors to be involved in its etiology. Most of the studies reported associations but not possible risk factors in the etiology of autism. The present work aimed at determining some epidemiological characteristics of Egyptian autistic children including the study of some incriminated perinatal factors. As well as biochemical assessment of metabolic disturbances with special stress on fatty acids and trace elements in the autistic children compared to their healthy siblings. Sixty children were included in the study, divided into two groups; a group that consisted of forty children who fulfilled the criteria of pervasive developmental disorders and a group of twenty apparently healthy siblings matched by age, sex, and social status to the autistic children. All the children were subjected to a thorough history taking and clinical examination including anthropometric measurements, Laboratory investigations included the determination of some routine biochemical parameters in blood and urine, serum and blood levels of some trace elements [copper, zinc, lead, and cadmium] using the atomic absorption spectrophotometry, serum total and individual fractions of fatty acids [using gas liquid chromatography] and urinary vanillyl mandelic acid [VMA]. The present work revealed a significant increase in head circumference measurement of autistic children compared to their control group and the gestational age as the only significantly different perinatal factor between th groups. A significant lower serum zinc and higher blood lead and cadmium mean values were observed in autistic children, along with significant rise in the ratios of copper to zinc, cadmium to zinc and lead to zinc. As regards the fatty acids, the omega 3 fatty acids were significantly lower in autistic children than the corresponding siblings, along with a significantly higher omega 6 to 3 ratio in autistic children in addition, the arachidonic acid ecosapentadecanoic acid ratio was significantly higher in autistic children than the corresponding siblings. Serum stearic acid was significantly higher while serum docosanoic acid and its methyl ester were significantly lower in autistic children than their healthy siblings. The urinary VMA and uric acid to creatinine ratios were .significantly higher in autistic children when compared to their healthy siblings. Correlation studies of omega 3 fatty acids with other parameters demonstrated positive correlation with serum zinc level and inverse correlations with blood lead, autistic head circumference, as well as lead/zinc, cadmium/zinc, urine uric acid and urine VMA to creatinine ratios. From the present work, it could be concluded that head circumference is an important determinant of autistic children. The disturbance in metal metabolism noted in this study by the significantly lower serum zinc which is important as a neurotransmitter and the significantly higher blood cadmium and lead levels could denote a dysfunction in metallothionein protective detoxification of cadmium and lead resulting in increased vulnerability these toxins. Another finding is the deficiency of essential fatty acid particularly the omega3 series including Eicosapentaenoic [EPA] and Docosahexaenoic [DHA] as well as the complete absence of linolenic acid could be responsible for the suppression of brain energy metabolism, and alteration of the course of brain development. In lion, neurochemical factors could play a role in autism as demonstrated by the increased urinary VMA in autistic children that denotes frequent stressful conditions to which autistic children are subjected to