مقالات پذیرفته شده در سومین کنگره بین المللی زیست پزشکی
Evaluating of Frequency of L67P and D76Y Polymorphisms in SOD1 Gene in ALS Patients
Evaluating of Frequency of L67P and D76Y Polymorphisms in SOD1 Gene in ALS Patients
Payam Bazyar,1,*Bagher Seyed Alipour,2
1. Master Student of Biochemistry, Faculty of Science, University of Mazandaran, Babolsar, Iran 2. Assistant Professor of Biochemistry, Faculty of Science, University of Mazandaran, Babolsar, Iran
Introduction: Amyotrophic lateral sclerosis is one forms of motor neuron disease and is a progressive and degenerative disease of nerve cells which is a result of the destruction of motor neurons and neurons in the brain and spinal cord that are responsible for the voluntary control of muscles. It causes muscle weakness and atrophy throughout the body. Many human neurodegenerative diseases show a phenotype of the accumulation of neural proteins. In ALS, superoxide dismutase 1 can accumulate abundantly in motor neurons. Recent studies have shown that this enzyme can transfer from one neuron to another in a mechanism similar to the release of prions and spread throughout the nervous system. There is no known cause of ALS for patients with no family history of the disease, accounting for 95% of cases. The known hereditary factor in ALS accounts for only five percent of all cases. An inherited genetic defect on chromosome 21 (coding for superoxide dismutase) is associated with 20% of familial cases of ALS. To date, 177 different mutations in SOD1 have been associated with this disease. Evidence suggests that lack of protection against oxidative stress regulates programmed cell death among many other possible consequences. Although it is not yet clear how mutations in the SOD1 gene lead to degeneration of motoneurons, researchers have theorized that free radical accumulation may be due to defective function of this gene. Based on what has been stated, the purpose of the present study was to evaluate the frequency of two L67P and D76Y polymorphisms in SOD1 gene in order to investigate the role of natural and mutant enzymes in ALS.
Methods: In this study, 60 individuals with familial ALS as case and 60 healthy controls as controls participated. 5 ml of blood samples were taken from these individuals and stored in EDTA tubes at -80 ° C. After DNA extraction using specific kit, PCR reaction for SOD1 gene was performed. Targeted polymorphisms were evaluated by RFLP method. Nla III enzyme for L67P polymorphism and Dde1 enzyme for D76Y polymorphism were used. Electrophoresis was performed on agarose gel to observe the results of the RFLP reaction. Statistical analysis was performed using SPSS software and ANOVA test.
Results: After observing the bands obtained by electrophoresis, based on the bands pattern, the genotype of each individual was determined for each polymorphism. Genotypic and allelic frequencies were also calculated for both polymorphisms studied in case and control groups. The results showed that the frequency of L67P and D76Y polymorphisms in SOD1 gene was significantly higher in individuals with familial ALS (P <0.05).
Conclusion: Superoxide is one of the reactive oxygen species in the cell and SOD plays a key antioxidant role. Mutations in SOD1 cause familial ALS. Genetic polymorphisms have been observed in SOD enzymes and their altered expressions and activities associated with oxidative DNA damage in various diseases including ALS. The results of the present study also confirm the association of L67P and D76Y polymorphisms with familial ALS in Iranian population suggests that these two polymorphisms can be used as genetic markers to predict ALS.