Study On The Deletion And Quantification Of SMN Gene In Sporadic Myotrophic Lateral Sclerosis

Objectives: To investigate the information of SMN deletions and SMN1/SMN2 copy number in sporadic amyotrophic lateral sclerosis (SALS) patients and normal controls of Chinese origin, to investigate the risk factors for SALS in Chinese.Methods: A total of 141 SALS patients and 134 unrelated controls were recruited from the Chinese population. Polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP) analysis were performed to screen SMN gene deletion. Frequencies of deletion were compared by Chi-square test.And then, we studied SMN1 and SMN2 genes copy numbers in 123 patients and in 171 matched controls by real-time fluorescence quantitative PCR.Logistic regression was used to compare freqencies of SMN1 and SMN2 copy number categories between patients and controls.Results: Four patients and 3 controls were detected to have homozygous SMN2 deletion. The frequencies of SMN2 deletion were 2.84% (4/141) and 2.24% (3/134), respectively, which was not significantly different (χ2 =0.0001, P = 1.000). No subjects were found to have homozygous SMN1 deletion.And we found an association of SALS with an abnormal copy number(one copy number)of SMN1 gene(p=0.002)with an OR of 3.508(1.601 to 7.687,95%CI). There is no correlation between SMN2 copy number categories and Chinese patients with SALS.Conclusions: There is no correlation between SMN gene deletion and Chinese patients with SALS.Abnormal SMN1 copy numbers(one copy number) are a genetic risk factor in sporadic amyotrophic lateral sclerosis.There was no effect of the SMN2 copy numbers on SALS risk.