Effects of fat mass and obesity-associated (FTO) gene polymorphisms on binge eating in women with binge-eating disorder: The moderating influence of attachment style

•No significant between-group differences were observed in this study for frequencies of FTO alleles.•FTO genotype interacted with attachment style to predict binge frequency.•rs1421085 interacts with insecure attachment in a way that may exacerbate binge eating. The genetics of binge-eating disorder (BED) is an emerging topic and one candidate pathway, namely the fat mass and obesity-associated (FTO) gene, may be implicated because of its role in food reward sensitivity and self-regulation of eating. The aims of this study were to examine the independent effects of variants of FTO on binge frequency in women with and without BED and to examine the moderating role of interpersonal attachment in this association. Secondary data analysis was conducted on a cross-sectional comparison of three groups of women in a trial of group treatment for BED: BED with obesity (n = 73), BED without obesity (n = 55), and normal weight without BED (n = 50). Women were genotyped for five of the most common FTO single-nucleotide polymorphisms, rs9939609, rs8050136, rs3751812, rs1421085, and rs1121980, which have been related to body mass index and energy intake. Binge frequency (Eating Disorder Examination), body composition (bioelectric impedance), and attachment (Attachment Style Questionnaire) were assessed. There were no significant between-group differences for frequencies of FTO alleles, nor were there any significant anthropometric associations. The FTO × attachment interaction was significant whereby, relative to a low-risk FTO genotype, individuals with a high-risk genotype for the SNP rs1421085 and high-avoidant attachment had higher mean binge frequency than those with high genetic risk but low-avoidant attachment (β = –7.96; t = –2.07; P = 0.042). FTO genotypes associated with risk for obesity and loss of control of eating, specifically rs1421085, may interact with insecure attachment in a way that may exacerbate binge eating among women with BED.