G C A T T A C G G C A T genes Review 5HTTLPR Genetic Variant and Major Depressive Disorder: A Review Caroline Fratelli 1 , Jhon Siqueira 2, Calliandra Silva 2 , Eduardo Ferreira 2 and Izabel Silva 2,* 1 Postgraduate Program in Health Sciences and Technologies, Campus Faculty of Ceilandia, University of Brasilia, Brasilia 72220-275, Brazil;
[email protected] 2 Department of Pharmacy, Campus Faculty of Ceilandia, University of Brasilia, Brasilia 72220-275, Brazil;
[email protected] (J.S.);
[email protected] (C.S.);
[email protected] (E.F.) * Correspondence:
[email protected]; Tel.: +55-(61)-3107-8400 Received: 26 August 2020; Accepted: 16 October 2020; Published: 26 October 2020 Abstract: Major Depressive Disorder (MDD) is a disease that involves biological, psychological, and social interactions. Studies have shown the importance of genetics contribution to MDD development. The SCL6A4 protein (5HTTLPR) functions transporting serotonin, a neurotransmitter linked to mood and emotion, to the synaptic cleft. Hence, this study seeks, through a literature review, a better comprehension of the 5HTTLPR genetic variant association with MDD. For this purpose, a search was performed on the Virtual Health Library Portal for articles that related 5HTTLPR to MDD. Most of the articles found were conducted in the American continent, with one (1) study implemented in Brazil. 5HTTLPR associations were found regarding changes in the nervous system, pharmacology, and risk factors seen in MDD patients. When verifying the allelic distribution, the S allele had a higher frequency in most of the studies analyzed. Despite not finding a commonality in the different studies, the tremendous genetic variation found demonstrates the MDD complexity.