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Association Study Between Serotonin Transporter Gene and Fluoxetine Response in Mexican Patients With Major Depressive Disorder

Camarena, Beatriz, MSc, PhD*; Álvarez-Icaza, Deni, MD; Hernández, Sandra, BSc*; Aguilar, Alejandro, MSc*; Münch, Lucía, MD, MSc; Martínez, Consuelo, MD*; Becerra-Palars, Claudia, MD, MSc

doi: 10.1097/WNF.0000000000000315
Original Articles

Objective Pharmacogenetic studies have identified genetic variants associated with fluoxetine response in patients with major depression disorder (MDD). The serotonin transporter gene is the principal site of action of selective serotonin reuptake inhibitors. Previous studies analyzing SLC6A4 gene variants are inconsistent and differ among populations. The aim of the present study was to analyze the association between 5-HTTLPR/rs24531 triallelic polymorphism and fluoxetine response in Mexican patients with MDD.

Methods We analyzed a sample of 150 patients with MDD. Fluoxetine response was assessed according to a reduction in the Hamilton Depression Rating Scale and Montgomery Depression Rating Scale scores of 50% or more at 8 weeks from baseline. In addition, we analyzed the genotype and allele distribution between responder and nonresponder patients in a subgroup of very severe depression patients.

Results We did not find association between fluoxetine responders and 5-HTTLPR/rs25531 variants (P = 0.0637). However, in the analysis of severe depression at baseline (Hamilton Depression Rating Scale ≥ 25), we observed a high frequency of low activity alleles (S/LG) in nonresponders patients (P = 0.0102).

Conclusions Our findings showed an association between low activity alleles of SLC6A4 gene and fluoxetine nonresponse in patients with severe depression.

*Departamento de Farmacogenética, and

Dirección de Servicios Clínicos, Instituto Nacional de Psiquiatría Ramón de la Fuente Muñiz, Mexico City, Mexico.

Address correspondence and reprint requests to Beatriz Camarena, MSc, PhD, Departamento de Farmacogenética, Instituto Nacional de Psiquiatria Ramón de la Fuente Muñiz, Calz. México-Xochimilco 101. Col. San Lorenzo, Huipulco. CP 14370. Mexico City, Mexico; E-mail:

Conflicts of Interest and Source of Funding: The authors have no conflicts of interest to declare.

This study was supported by FOSISS CONACYT Grant 261459 and Cátedras CONACYT Grant 1683.

Funding was provided by “Consejo Nacional de Ciencia y Tecnología” (CONACYT) Grant FOSISS 261459 to B.C. Some of the equipment used in the present study was kindly financed by CONACYT (Cátedras CONACYT Grant 1683) to C.B.P.

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