Analysis Of Natural History Of Spinal Muscular Atrophy In 117 Children

Objective: To analyze the natural history and the survival status of SMA children in Southwest China,and to provide references for the comprehensive management of SMA,gene modification therapy,and to improve the quality of life of SMA children.Methods: The data of 117 cases of SMA were analyzed retrospectively.The characteristics and differences in epidemiology,demography,age,clinical manifestations,nerve conduction,electromyography,SMN1 gene and survival time were compared.The risk factors of increasing SMA1 death were analyzed.SPSS 23.0 was used for statistical analysis.Results: There were 117 cases of SMA in this study,male: female = 1.43:1,type 1,type 2 and type 3 SMA were 62,45 and 10,respectively.The average age of onset was 2.29±2.20 months,11.29 ± 5.22 months and 17.60 ± 7.53 months.The age difference of onset,first visit and diagnosis of type 1 SMA was greater than that of type 2 and type 3.Myasthenia(85.5%)was the main onset mode in SMA,and pneumonia(14.5%)could be found in onset mode of type 1.The main clinical manifestations were weakness(100%),hypotonia(100%)and disappearance of tendon reflex(98.1%).Head control weakness,crying weakness and eating difficulty were more likely to occur in type 1 SMA(P<0.05).The rate of homozygous deletion in exon 7 of SMN1 gene was 99.2%,and the most common gene mutation was exon 7 homozygous deletion(68.4%).There was no difference in the detection rate among different types(P>0.05).The survival rate of type 1 was significantly lower than that of type 2 and type 3 SMA(P=0.00).The survival rates were 53.2% at 6 month,27.80% at 1 years,20.9% at 2 years,17.4% at 3 years,15.4% at 4 years,15.4% at 5 years,and 10.3% at 6 year.K-M single factor analysis and multivariate Cox regression analysis showed that the onset of pneumonia and head weakness were independent risk factors for SMA.Conclusion: Early onset of SMA was common in infants,but it was difficult for most patients to see a doctor and make a diagnosis.Myasthenia was the main onset mode in SMA,and pneumonia could be found in onset mode of type 1.Myasthenia,hypotonia and disappearance of tendon reflex were the main manifestations of SMA,and there were different clinical types.Homozygous deletion of exon 7 of SMN1 gene was the main type of gene mutation,which could be used to diagnose SMA.The mortality rate of SMA 1 was high,and the 5-year survival rate was 15.4%.The onset of pneumonia and the weakness of the head were the independent risk factors affecting the prognosis of SMA 1.The survival rate of Type 2 and Type 3 were high,the motion regression could be non-linear regression,and the quality of life was poor.