Correlation Study Between The Gene Polymorphism Of Endothelin 1 And Vasovagal Syncope In Children

Objective: This study sought to analyze the distribution of vascular endothelin 1(ET-1)+138A/-gene polymorphism in children's vasovagal syncope(VVS)and the associated clinical classification groups,and to investigate the correlation between them.Methods: A head-up tilt test(HUT)was performed in children visiting Our hospital from January 2016 to June 2018 for unexplained syncope.A total of 80 cases of HUT positive and VVS diagnosed children were enrolled and assigned to the VVS group.The VVS group was further divided into 3 subgroups according to the clinical classification.A total of 80 children with negative HUT were enrolled and assigned to the HUT-negative group.A total of 80 healthy children were enrolled as the normal control group.The clinical characteristics of children in VVS group and HUT-negative group were recorded and venous blood samples of each subject were collected.ET-1+138A/-polymorphism was evaluated using high-resolution melting curve and polymerase chain reaction together with gene sequencing.The genotype and allele frequency were analyzed and compared between different groups and VVS subgroups.Chi-square test was used to test statistical significance(P<0.05).Results: The VVS group and the HUT-negative group exhibited different gender distributions.The percentage of females was significantly higher than males who had VVS(P<0.05),and the difference was statistically significant.The +138A/-genotypes in the VVS,HUT-negative,and normal control groups were 3A/3A:42?57?52;3A/4A:34?21?23;4A/4A:4?2?5.The allele frequencies in the VVS,HUT-negative,and normal control groups were 3A:118?135(84.4%)?127;4A: 42?25?33.The distribution of genotypes and allele frequencies didn't show statistically significant differences between the three groups(P>0.05).The 80 children in the VVS group were further divided into three subgroups,and the +138A/-genotypes in the mixed-response subgroup(19,23.8%),cardioinhibitory-response subgroup(27,33.7%)and vasodepressor-response subgroup(34,42.5%)were 3A/3A:13?19?10;3A/4A: 5 ? 7 ? 22;4A/4A:1 ? 1 ? 2.The allele frequencies in the mixed-response,cardioinhibitory-response and vasodepressor-response subgroups were 3A:31?45?42;4A:7?9?26.3A4 A and 4A alleles had significantly higher percentages in the vasodepressor-response subgroup than other two subgroups(P<0.05).Conclusion: The association between ET-1+138A/-polymorphism and VVS was not found in the population of this study.However,the 3A4 A genotype and 4A allele were highly distributed in the vasopressor-response subgroup than other VVS subgroups,presumably due to the correlation between the ET-1+138A/-and the blood pressure regulation during the onset of VVS.