The Collection And Gene Analysis Of Two Pedigrees With Suspected Hereditary Spastic Paraplegia From Guizhou

Objective: To establish the diagnosis procedure of Hereditary Spastic Paraplegia(HSP), improve the understanding of HSP in pediatricians, fill HSP gene bank and provide the basis for the gene diagnosis of hereditary diseases of nervous system in Guizhou province by clinical observation of pedigrees with suspected HSP, whole exome sequencing of propositus and gene verification of pedigree members. Methods: ①The clinical data of proposituses in two pedigrees with suspected HSP were collected including symptoms, physical signs and results of medical imaging and nerve electrophysiology. Blood samples were also collected and family genetic map was plotted. Then, the inheritance patterns and possible genotypes of the two pedigrees were analyzed. ②The clinical data and blood samples of total 17 people of the two pedigrees were collected at the place of residence, and DNA were extracted and stored. ③Whole exome sequencing was performed for proposituses.(4) Sanger sequencing was used to examine other pedigree members and the control group followed by variation explanation and verification of candidate variant genes. Results: ①Proposituses of the two pedigrees all showed tractus pyramidalis injury with slow progression which was the main clinical feature. Suspected HSP was diagnosed based on the results of nerve electrophysiology and MRI of spinal cord and family histories of patients and the exclusion of other diseases. ②3 patients were found in pedigree 1 with secondary attack, among which 2 showed similar clinical symptoms to proposituses but differences were noted. 1 patient was found with epicophosis and the other with dysplasia and mental subnormality; 6 patients were found in pedigree 2 with successive attack in four generations. The clinical symptoms were similar to proposituses only with different severities and anticipation was noted. ③Whole exome sequencing of proposituses in pedigree 1 suggested that the disease genes were SPG3 A, SPG11, SPG12 and SPG48, which were normal in other pedigreemembers after verification. For proposituses in pedigree 2, the results of whole exome sequencing and the verification by Sanger sequencing revealed that the disease gene was BICD2(c.1203G>T,p.Gln401 His, missense mutation). Conclusion: In the two pedigrees with suspected HSP, pedigree 1 showed complex clinical symptoms, indicating stronger probability of polygenic disease and HSP was excluded. For pedigree 2, the disease gene was clarified as BICD2, which is relevant to gene variation and HSP morbidity based on gene bank reference and previous studies. These findings, together with the results of clinical and auxiliary examinations, confirmed the diagnosis of HSP. This study enhances the understanding of HSP in clinical physicians and suggests the importance of inheritance patterns in the diagnosis of gene disease. The combination of clinical analysis and gene diagnosis improves the accurate diagnosis rate of HSP and lays the foundation for the lunching of gene diagnosis and prenatal genetic screening in our hospital.