الفهرس 
INTRODUCTION AND AIM OF THE WORKOnly 14 pages are availabe for public view
Abstract
The autism spectrum describes a range of conditions classified as neu-rodevelopment disorders in the fifth version of the American psychiat-ric association’s diagnostic manual disorders 5th edition (DSM-5). These disorders are characterized by social deficits and communication difficulties, stereotyped or repetitive behaviors and interests, sensory issues and in some cases cognitive delays, American Psychiatrics Pub-lishing (2013).
MT is a biologically essential protein that has shown to be heavily in-volved in the metal regulation of zinc and copper as well as the chelat-ing of toxic metals such as mercury. Also MT proteins assist in immune function, neuronal development, energy metalothionine and have anti-oxidant properties.
Studies showed that MT could not function properly in autistic chil-dren although it is still unclear wither this is due to genetic factors simply low levels of MT in the body Anderwis (2015).
While genetic factors are clearly important, as indicated by high con-cordance rates among twins and siblings, they alone cannot account for an epidemic that developed in the relatively short period of 10-20 years, Herbert and Russo (2010).thus environmental factors are very likely to account for the major portion of the increased prevelance of autism.
Exposure to xenobiotics is an inevitable feature of contemporary life driven by an ever increasing number of threating chemicals found in air/water and food supplies and other materials we come in contact with during our daily routine, Death et al., (2008).
Mercury is a well-known neurotoxin. Three kinds of mercury exposure : elemental mercury, as well as poisoning, inorganic and organic mer-cury which are the most toxic forms. Cheny et al., (2007).
Moreover it is possible that individual vulnerability to toxic environ-mental exposure varies according to nadditive and interactive effects of multiple effects of multiple genetics and polymorphisms that negatively affect detoxification capacity, Lichtens et al., (2010). Because the risk of developmental toxicity with low dose environmental chemicals is likely to be influenced by individual genetic determination of suscepti-bility Gurney and Isere, (2013).
Regressive autism refers to children who have normal development un-til the age of 1 to 2 years, after which there is a loss of language, social interaction, and other developmental mile stones. It is mainly this type of autism that has caused the widespread public concern over the influ-ence of the measles mumps rubella (MRR) and mercury-containing vac-cines on the development of autism New mark, (2007).
The present study was conducted on 31 Autistic children, 90% autistic children were diagnosed before the age of 3 years. Autistic group age from 2-11 years these finding are in agreement with Gray and Tohgue (2001). All patients and control were subjected to the following: envi-ronmental exposure to mercury, IQ assessment (intelligent Quotient) using Stanford Benet intelligence scale (1986), Assessment of autistic Symptoms using child good autism rating scale CARS Schoplek et al., (1986) and genotyping was done after DNA extraction RCR amplifica-tion by using primer MT1A, MT1E.
The results of this study showed that there is highly significant differ-ence between autistic patients and controls as regarding mercury levels P<0.001**
There was no significant difference in CARS assessment regarding Hg levels.
Children with MT1 A genotype showed high significance in MT1A as regarding AG (P<0.001**)
Children with MT1E genotype showed high significance in MT1E regarding GG (P<0.001**)
On the contrary mercury levels showed no significance in MT1A and MT1E .