Gene Sequence Analysis Of Hereditary Spastic Paraplegia Pedigree PLP1

Objective: Hereditary spastic paraplegia is a kind of inherited and neurodegenerative diseases, with significant genetic heterogeneity. The patients have slowly progressive lower extremity spastic paraplegia, scissors gait which lately occurred in the upper limbs . The diseases had high disability and seriously affected quality of life. Now there is no special treatment , so the only way to prevent sick children from born is prenatal diagnosis .At the same time ,this method is the most important factor which can improve the quality of people's life . DNA sequences of a hereditary spastic paraplegia pedigree were detected in order to explore the family's gene mutation sites and further the value of clinical application.Methods: Genomic DNA was extracted from blood samples of a hereditary spastic paraplegia pedigree , SPG2 was posited through the clinical symptoms and genetic mode. PLP1 was disease-causing genes. First cloning primers were designed , PLP1 exon3, exon5 were amplified by PCR, when the amount reached a certain level, products were recycled. Second PLP1 exon6, exon7 amplified by PCR were connected with T vector after recycling ,then transformed . Bacteria were shook and plasmid was extracted. PLP1 exon3, exon5 and exon6,exon7 were sent to sequence. Results of the sequencing was detected by nucleic acid and protein sequence comparison used DNAMAN Version5.2.RESULTS: After PCR amplification and sequencing, exon3,exon5 and exon7 fragments obtained were the same to PLP1 sequence published by the NCBI; Point mutation occurred in the 844th base in exon6 of the 10th sample. The change that T mutated to C caused the change of the amino acids that phenylalanine changed to leucine. Although the 844th base is C exon6 on the 5 samples found in pairs for the C, gene sequencing analysis showed the mixed-signal of T signal and C signal, so the possibility of this point mutation was not temporarily excluded. Until now this mutation point has not been reported, remains to be further explored.Conclusion: 1. Detection method of SPG2 gene of hereditary spastic paraplegia was successfully established .This method can be used early genetic diagnosis and prenatal diagnosis of X-recessive hereditary spastic paraplegia.2. A new gene mutation sites has been founded by sequencing. The gene mutation sites has not been reported at home and abroad and remains to be further studied.3. The 844th base of exon6 in PLP1 gene of the proband of the pedigree existed mutation that T instead of C, so far, this mutation has not been reported. A new genetic mutation site was added in the genetics. the 844th base is C exon6 on the 5 samples found in pairs for the C, gene sequencing analysis showed the mixed-signal of T signal and C signal, so the possibility of this point mutation was not temporarily excluded4 .The changes that phenylalanine changed to leucine may lead to degeneration of the corticospinal tract axons and demyelination and cause a series of clinical symptoms including muscle tone increased, walking laborious.5. Clinical symptoms of hereditary spastic paraplegia were varied. The gold diagnosis standard is genetic testing.6.This study provided basic research for further gene therapy. Abnormal gene was suppressed through gene regulation in order to achieve therapeutic purposes.