Association between 5-HTTLPR polymorphism, suicide attempt and comorbidity in Mexican adolescents with major depressive disorder

Introduction. The World Health Organization reports that suicide is among the leading causes of death for young people. Depression is the most frequently related disorder with suicidal behaviors. There is increasing evidence that suicidal behavior has a strong genetic contribution. Several studies report an association between the genotype "SS" and the "S" allele of the 5-HTTLPR polymorphism of the serotonin transporter gene and suicidal behavior. The aim of the study was to determine the association of variants of the serotonin transporter gene with suicidal attempt and co-morbidity in depressed adolescents. Methods. The frequencies of ss genotypes and s allele were compared between a sample of 200 adolescents with a diagnosis of depression and the antecedent of a suicide attempt who were evaluated with K-SADS-PL and a group of 235 healthy controls. Genotyping of the 5-HTTLPR polymorphism was performed by PCR. Results. Analysis of the frequencies of genotypes and alleles showed a statistically significant difference between the groups (Genotypes: x2=11.1, df=2, p=0.004, Alleles: x2=11.9, df=1, p=0.0009). There were no associations with comorbid disorders. Conclusions. The results support the hypothesis that the serotonin transporter gene, specifically the s allele and the ss genotype of the 5-HTTLPR polymorphism, are related to the history of depression and suicide attempt in adolescents.