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Are GSTMl Null and GSTTl Null Risk Factorof Autism Spectrum Disorder? A Preliminary Study

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Background: Low plasma total glutathione (tGSH) levels, elevated levels of oxidized glutathione (GSSG) and low ratios of tGSH to GSSG in autism were reported. Glutathione S-transferases (GST) are antioxidant enzymes that play important role in cellular detoxification and the excretion of environmental pollutants including heavy metals. Glutathione S-transferase mu (GSTM1) and Glutathione S-transferase theta (GSTT1) are known to be highly polymorphic. Homozygous deletions of these genes result in lack of enzyme activity and impaired the ability to excrete metals including mercury. Combined effects of mercury (Hg) accumulation coupled with decreased levels of antioxidants (low glutathione and antioxidant enzymes) contribute to the phenotypic presentation of autism spectrum disorder (ASD). Association of GSTMI null genotype with autism has been reported. Therefore the preliminary study was performed to investigate the role of GSTM1 null and GSTT1 null as risk factor of ASD associated with phenotype express ion.
Method: Fifty one ASD patients were recruited from special need & autism school and 45 controls from Semarang & Solo. Blood veins samples were collected and genomic DNA was extracted by salting-out method in CEBIOR Semarang. Genotyping for GSTM1 and GSTT1 gene was done in UMBI Malaysia. Multiplex PCR was performed and PCR products were separated on 1.2 % agarose gel, stained with ethidium brom ide and visualized on UV transiluminator. GSTM1 & GSTT1 gene product is about 625 bp and 459 bp. Absence of GSTMI and GSTT1 gene band was interpreted as GSTM1 null & GSTT1 null.
Results: The frequency of GSTM1 null and GSTT1 null in ASD higher compared with control group but the dijference is not statistically significant (p=0.357, OR=0.504; 95% CI 0.117-2.168 and p=0.364, OR=0.674; 95% CI 0.287-1.580). There is also no statistica/ly dijferent in the distribution of GSTMJ null and GSTTJ null between mild to moderately autistic and severely autistic (p=0.983, OR=0.lA80; 95% CI 0.158-6.095 and p=0.439, OR=1.633; 95% CI 0.471-5.656).
Conclusion: GSTM1 null and GSTT1 null are not risk factor of ASD. Further investigations are needed with a bigger sampie size, analyzing multiple GST genes and GST activity determination to find out the gene susceptibility of ASD and factors that contribute to the phenotype expression of ASD.
Keywords: GSTM1 null, GSTT1 null, risk factor, autism spectrum disorder

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Call Number

Media Medika Indonesiana, 46 (2) 2012 : 69-74

Publisher

: FK Diponegoro Semarang., 2012

Collation

6p

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ISBN/ISSN

0126-1762

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Subject(s)

AUTISTIC DISORDER

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