Association of the SLC6A4 gene 5HTTLPR polymorphism and ADHD with epilepsy, gestational diabetes, and parental substance abuse in Mexican mestizo children

Introduction. Attention deficit hyperactivity disorder (ADHD) is one of the most common neuropsychiatric conditions in childhood and a multifactorial condition attributable to genetic and/or environmental influence. Allelic variants in the serotonin transporter gene ( SLC6A4 ) have been associated to lower transcriptional efficiency, changes in serotonin concentration in several brain regions, and ADHD development. Objective. To identify the association between the SLC6A4 alleles and ADHD diagnosis and risk factor phenotypes in children from a Mexican mestizo population. Method. In this study, 134 unrelated children were included and evaluated for ADHD, genotypification for the 5HTTLPR polymorphism, and identification of multiple phenotypes from their clinical records and family background for association analysis. Results. The following distribution of genotypes was observed: 23% SS, 49% SL, and 28% LL. From the phenotypes evaluated in the present study, gestational diabetes mellitus ( p = .045), history of epilepsy ( p = .047), and parental substance abuse ( p = .033) showed an association with ADHD development in regression analysis along with the S variant. Discussion and conclusion. Results suggest that interaction of the S allele and some of the phenotypes analyzed may play a relevant role in the development of ADHD in the studied population.