The Transmission Disequilibrium Study Of Serotonin Transporter Gene And Attempted Suicide With Family-based System

Objective To investigate the association between promoter (5-HTTLPR) and 3'untranslated region (5-HTT-3'UTRG/T) polymorphisms of the serotonin transporter (5-HTT) gene and suicidal behavior.Methods 154 parent-offspring trios with suicide attempts were involved in the study. A self-compiled family questionnaire referred to the Family Interview for Genetic Studies (FIGS) and some psychological rating tools were used to assess the participants, and diagnostic assessment was made by the 4th edition of Diagnostic and Statistical Mental Disorders Criteria (DSM-IV). The genotypes of two polymorphisms (5-HTTLPR and 5-HTT-3'UTRG/T) in 5-HTT gene were determined by using polymerase chain reaction (PCR) and restriction fragment length polymerase (RFLP) techniques. The data were analyzed with family-based systemic haplotype-based-haplotype relative risk and transmission/disequilibrium test. There are 105 suicide attempts core families. The diagnostic assessment was made according to the DSM-IV by two psychiatrists whose titles are above attended doctors.Results (1) No significant difference between patient group and parent group in genotype and allele frequency of 5-HTTLPR (χ~2=0.390,р=0.823;χ~2=0.416,р=0.519). (2) No significant difference between patient group and parent group in genotype and allele frequency of 5-HTT-3'UTRG/T (χ~2=2.055,р=0.358;χ~2=0.178,р=0.673). (3) HHRR showed there are no significant difference of genotype frequency of 5-HTTLPR between patient group and control group (χ~2=1.226,р=0.268). (4) HHRR showed there are no significant difference of genotype frequency of 5-HTT-3'UTRG/T between patient group and control group (χ~2=0.528,р=0.468). (5) TDT analysis did not show transmission disequilibrium between suicide attempts and 5-HTTLPR (χ~2=3.704,р>0.05). (6) TDT analysis did not show transmission disequilibrium between suicide attempts and 5-HTT-3'UTRG/T (χ~2=2.571,р>0.05). (7) TDT analysis showed transmission disequilibrium between suicide attempts 5-HTTLPR and with psychiatric diseased core families (χ~2=4.263, p<0.05), but there no transmission disequilibrium between suicide attempts and 5-HTT-3'UTRG/T (χ~2=1.899, p>0.05).Conclusion (1) The 5-HTTLPR polymorphisms of the 5-HTT were associated with psychiatric attempted suicide. (2) The 5-HTT-3'UTRG/T polymorphisms were associated with suicide behavior. (3) The 5-HTT gene may play a role in the inheritance of suicide.