Genetic Screening Of Spinal Muscular Atrophy(SMA) In Pregnant Women

Objective:Through screening of pregnant women with spinal muscular atrophy(SMA)mutations in Qingdao area,we have a preliminary understanding of the carrying probability of abnormal SMN gene copy number in pregnant women in this area.This experimental protocol can be used as a prospective study to provide ideas for establishing preliminary clinical prenatal screening methods which are easy,fast and accurate targeting of SMN gene.Through this screening method,we can effectively prevent and block the birth of children with spinal muscular atrophy,and improve the quality of the population in the region.Methods:The first part of this study mainly focused on 1118 pregnant women who attended the obstetrics clinic of Qingdao University Affiliated Hospital from January to December 2019.We have tested the copy number of SMN1 and SMN2 genes in pregnant women by combining the application of multiplex PCR and denaturing high-performance liquid chromatography(DHPLC).Based on this,we determined whether the pregnant women are carriers,and calculated the probability of carriers.The husband of the pregnant woman of the carrier is the object of the second part of the study.After screening the pregnant woman carrier,contact the spouse according to the contact information of the medical card and recommend the same method to detect the SMN genotype of the spouse.Fetal prenatal diagnosis excludes the possibility of fetal illness.The object of the third part of the study is the fetus of both the couple and the carrier.The amniotic fluid cells are sent to the test,and the SMN genotype of the fetus is detected in the same way.Experimental results:The experimental results show that the ratios of SMN1 and SMN2 genes in the 1118 cases are of the following types: 2: 0,1: 1,2: 1,3: 1,1: 2,2: 2,2: 3,0: 3,3: 2,1:3,in addition to 10 samples with abnormal peak shapes and further measurements required.Among them,1: 1,1: 2 and 1: 3 are carrier gene ratios,there are 19 cases with a probability of 1.71%.In addition,there is another 0: 3 situation,which is a morbid situation.Among the 19 carrier spouses tested in the second part of the experiment,one carrier was found and the amniocentesis was sent to the pregnant woman's intrauterine fetus.The fetus was also a carrier with a copy number of 1 for SMN1.Conclusion:1.This experiment tested 1108 pregnant women.The detection rate of SMA carriers was 1.71%,which was in line with the probability range of SMA epidemiological carriers(1.67%-2.50%).2.Compared with other gene screening technologies,the DHPLC protocol used in the experiment has the advantages of high sensitivity,strong specificity,low cost,and less time consumption.It is very helpful for establishing a cheap and effective pregnant women SMA screening.However,for "2 + 0" carriers,there is still a lack of effective screening methods,which is an important direction for the development of SMA screening technology at this stage.3.The experiment uses amniocentesis to obtain fetal genes for detection,which excludes the possibility of a suspicious fetus.Therefore,the invasive prenatal diagnosis method is still of great value in the diagnosis of high-risk genetic diseases.