Association Between Gene Polymorphism Of Serotonin Transporter Gene Promoter (5-HTTLPR) And Monoamine Oxidase A (MAOA)and Oppositional Defiant Disorder (ODD) In Children

Objective Through analyze the association between gene polymorphism of serotonin transporter gene promoter (5-HTTLPR) and monoamine oxidase A (MAOA) and oppositional defiant disorder (ODD) in children to find the susceptibility gene of ODD in children.Methods123ODD children and134healthy children were involved in this case-control study. Restriction fragment length polymorphism analysis was performed to detect the association between gene polymorphism of5-HTTLPR and MAOA and ODD. The two alleles were closely related to5-HT transport and degradation. The frequencies of genotype and allele were compared between the ODD group (n=123) and controls (n=134).Results①The5-HTTLPR genotypic distributions in ODD group and controls was that the SS genotypes (103/123) were more than SL genotypes (13/123) in ODD group, but compared with controls (SS=101/134, SL=22/134), no significant differences were found(x2=2.634, P=0.085; x2=1.978, P=0.127). But statistics results showed that the SS genotype may increase the risk of children’s impulsive behaviors (odds ratio=1.689). No significant differences were found between ODD group and controls (P>0.05).②The5-HTTLPR allelic distributions in ODD group and controls was that the L alleles were less in ODD group (22/246) versus controls (37/268). Significant association was found (x2=4.018, P=0.039); the S alleles were more in ODD group (221/246) versus controls (227/268). Significant association was found (x2=3.901, P=0.067).The statistics results showed that the S allele may increase the risk of children’s ODD (odds ratio=1.431). ③The MAOA-uVNTR genotypic distributions between ODD patients and controls was that the4.5/4.5genetypes (2/123) in ODD group were less than controls (14/121), significant association was found (x2=6.092, P=0.003).5/5genetype between ODD patients (30/123) and controls (17/121) was fond slightly significant association (x2=5.137, P=0.047, Fisher’Exact T=0.057). The statistics results showed that lack of4.5/4.5genotype or exciting5/5genetype may increase the risk of children’s ODD.No significant association was found in the other genetypes between ODD patients and controls (P>0.05).④The MAOA-uVNTR allelic distributions in ODD patients and controls was that the4.5R alleles in ODD group (4/246) were significantly less than controls (28/242), significant association was found (x2=14.310, P=0.000);5R alleles in ODD group (65/246) were significantly more than controls (38/242), significant association was found (x2=9.131, P=0.003, Fisher’ Exact T=0.004). The statistics results showed that the5R allelie may increase the risk of children’s ODD (odds ratio=1.897).⑤The MAOA-uVNTR genotypic distributions between in male children ODD patients and controls:male children’s ODD,4/4(35/70).4.5/4.5(0/70).5/5(20/70); controls4/4(44/66).4.5/4.5(7/66).5/5(5/66).Significant association was found in4/4genotype (x2=5.173, P=0.029, Fisher’ Exact T=0.039); slightly significant association was found in4.5/4.5genotype (x2=4.276, P=0.048, Fisher’ Exact T=0.073); significant association was found in5/5genotype (x2=7.132, P=0.007, Fisher’ Exact T=0.006). The statistics results showed that lack of4/4genotype or5/5genetype may increase the risk of male children’s ODD (odds ratio=3.824). No significant association was found in the other genetypes between male children’s ODD and controls (P>0.05).⑥The MAOA-uVNTR allelic distributions between ODD patients and controls in male children:male children’s ODD,4R(74/140).4.5R(0/140).5R (43/140); controls,4R(89/132).4.5R(14/132).5R(11/132). Significant association was found between the two groups.(x2=6.014, P=0.007, Fisher’ Exact T=0.007; x2=6.302, P=0.005, Fisher’ Exact T=0.007; x2=14.891, P=0.000, Fisher’ Exact T=0.000). The statistics results showed that the5R allele may increase the risk of children’s ODD (odds ratio=3.821).Conclusions①The S allele of5-HTTLPR may increase the risk of children’s ODD;②The L allele of5-HTTLPR may be the protect factor of children’s ODD;③The lack of4.5/4.5genotype of MAOA-uVNTR or existing5/5genetype may increase the risk of children’s ODD;④The5/5genetype of MAOA-uVNTR may be risk factor in male children’s ODD, and4/4genetype may be protect factor.