Differences in body mass index according to fat mass- and obesity-associated (FTO) genotype in Mexican patients with bipolar disorder

• Published in: Bipolar disorders 2015-09, Vol.17 (6), p.662-669
• Main Authors: Díaz-Anzaldúa, Adriana, Ocampo-Mendoza, Yolanda, Hernández-Lagunas, José Octavio, Díaz-Madrid, Federico Alejandro, Romo-Nava, Francisco, Juárez-García, Francisco, Ortega-Ortiz, Hiram, Díaz-Anzaldúa, Alejandro, Gutiérrez-Mora, Doris, Becerra-Palars, Claudia, Berlanga-Cisneros, Carlos
• Format: Article
• Language: English
• Subjects: Alleles; Alpha-Ketoglutarate-Dependent Dioxygenase FTO; antipsychotic agents; Antipsychotic Agents - pharmacology; bipolar disorder; Bipolar Disorder - diagnosis; Bipolar Disorder - drug therapy; Bipolar Disorder - epidemiology; Bipolar Disorder - genetics; Bipolar Disorder - physiopathology; Body Mass Index; Diagnostic and Statistical Manual of Mental Disorders; Female; FTO gene; gene for human fat mass- and obesity-associated protein; Genotype; Humans; lithium carbonate; Male; Mexico; Middle Aged; obesity; Obesity - diagnosis; Obesity - epidemiology; Obesity - genetics; Obesity - psychology; Proteins - genetics; rs8050136; rs9939609; valproic acid
• ISSN: 1398-5647; 1399-5618
• DOI: 10.1111/bdi.12328

Objectives The prevalence of obesity has dramatically increased in many countries and it is particularly high in patients with bipolar disorder (BD). A region in the first intron of the fat mass‐ and obesity‐associated (FTO) gene, encompassing markers rs9939973, rs8050136, and rs9939609, has been consistently associated with obesity and body mass index (BMI) in different populations. We sought to determine whether FTO is associated with BMI and/or obesity in patients with BD. Methods The sample included 129 Mexican Mestizo patients with bipolar I or bipolar II disorder. After obtaining informed consent, participants were evaluated with the Structured Clinical Interview for DSM‐IV Axis I Disorders and weight, height, and body measurements were recorded. DNA was extracted from a 5‐mL blood sample and real‐time polymerase chain reaction was performed. The results were analyzed with Haploview v4.2 and SPSS v21. Results Differences in mean BMI were explained by rs8050136 and rs9939609 genotypes, especially by comparing non‐carriers and carriers of two copies of the risk allele (Tukey's p ≤ 0.019), with a mean difference in BMI as high as 7.81 kg/m2. Differences in BMI were also explained by the interaction of the genotype (rs8050136 and/or rs9939609), the use of second‐generation antipsychotics, and the use of mood stabilizers (p ≤ 0.41). Obesity was also associated with these two markers when patients with and without obesity were compared. Conclusions In patients with BD, differences in BMI may be affected by the presence of FTO risk alleles, especially in homozygous individuals for these variants. Besides evaluating the possible metabolic effects of certain antipsychotics or mood stabilizers, it is important to evaluate the role of other factors such as FTO risk alleles.