Association between obesity and the brain-derived neurotrophic factor gene polymorphism Val66Met in individuals with bipolar disorder in Mexican population
Received 20 January 2016
Accepted for publication 15 March 2016
Published 25 July 2016 Volume 2016:12 Pages 1843—1848
Checked for plagiarism Yes
Review by Single-blind
Peer reviewers approved by Dr Xiang Mou
Peer reviewer comments 2
Editor who approved publication: Dr Roger Pinder
Mirna Edith Morales-Marín,1 Alma Delia Genis-Mendoza,1,2 Carlos Alfonso Tovilla-Zarate,3 Nuria Lanzagorta,4 Michael Escamilla,5 Humberto Nicolini1,4
1Genomics of Psychiatric and Neurodegenerative Diseases Laboratory, National Institute of Genomic Medicine (INMEGEN), CDMX, Mexico; 2Psychiatric Care Services, Child Psychiatric Hospital Dr Juan N Navarro, CDMX, Mexico; 3Genomics Research Center, Juarez Autonomous University of Tabasco, Comalcalco, Mexico; 4Carracci Medical Group, CDMX, Mexico; 5Department of Psychiatry, Paul L Foster School of Medicine, Texas Tech University Health Science Center, El Paso TX, USA
Background: The brain-derived neurotrophic factor (BDNF) has been considered as an important candidate gene in bipolar disorder (BD); this association has been derived from several genetic and genome-wide studies. A polymorphic variant of the BDNF (Val66Met) confers some differences in the clinical presentation of affective disorders. In this study, we evaluated a sample population from Mexico City to determine whether the BDNF (rs6265) Val66Met polymorphism is associated with the body mass index (BMI) of patients with BD.
Methods: This association study included a sample population of 357 individuals recruited in Mexico City. A total of 139 participants were diagnosed with BD and 137 were classified as psychiatrically healthy controls (all individuals were interviewed and evaluated by the Diagnostic Interview for Genetic Studies). Genomic DNA was extracted from peripheral blood leukocytes. The quantitative polymerase chain reaction (qPCR) assay was performed in 96-well plates using the TaqMan Universal Thermal Cycling Protocol. After the PCR end point was reached, fluorescence intensity was measured in a 7,500 real-time PCR system and evaluated using the SDS v2.1 software, results were analyzed with Finetti and SPSS software. Concerning BMI stratification, random groups were defined as follows: normal <25 kg/m2, overweight (Ow) =25.1–29.9 kg/m2, and obesity (Ob) >30 kg/m2.
Results: In the present work, we report the association of a particular BMI phenotype with the presence of the Val66Met allele in patients with BD (P=0.0033 and odds ratio [95% confidence interval] =0.332 [157–0.703]), and correlated the risk for valine allele carriers with Ow and Ob in patients with BD.
Conclusion: We found that the methionine allele confers a lower risk of developing Ow and Ob in patients with BD. We also confirmed that the G polymorphism represents a risk of developing Ow and Ob in patients with BD. In future studies, the haplotype analysis should provide additional evidence that BDNF may be associated with BD and BMI within the Mexican population.
Keywords: brain-derived neurotrophic factor, bipolar disorder, single nucleotide polymorphism, body mass index
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