My interest in polygenic traits, which are traits influenced by multiple genes, and the intricate genetic architecture of diseases was piqued during discussions in genetics class. This led to a deep reflection on my battle with anorexia nervosa. The complex interplay of multiple genes in conditions like coronary heart disease and obesity mirrored the multifaceted nature of my struggle with body image and the desire to nourish myself amidst societal pressures.
My life took a significant turn in 2022 during a work trip to Madagascar, where a monotonous diet of rice and beans, due to the limited food options, triggered an aversion to these staples upon my return. A seemingly innocuous comment about portion sizes heightened my body awareness, which quickly spiralled into anorexia. Within months, I experienced a drastic 40% weight loss, plummeting my BMI to a dangerously low level that necessitated admission to an eating disorder treatment facility. This experience underscored the urgent need for early intervention in anorexia, a condition that can rapidly escalate without timely support and treatment.
Looking back, the confluence of events and predispositions seems both evident and deeply layered. My formative years as a dancer instilled an unspoken pressure for leanness, undoubtedly shaping my body image. The environmental trigger of the restrictive diet in Madagascar, coupled with the triggering comment, ignited an obsessive focus on my body, leading to meticulous calorie counting and severely restricted eating habits. My diet dwindled to a single daily meal of green vegetables. The ensuing rapid weight loss, though alarming to those around me, was strangely imperceptible to my distorted self-perception. It was the growing concern of my girlfriend, who provided unwavering support and understanding, a friend with a history of eating disorders, and others, that began to penetrate my denial. The stark reality of my emaciated state finally hit me during a Christmas visit home, when my horrified parents took me to a doctor, and I was confronted with my reflection after the medical assessment.
However, the genetics discussions in class sparked a crucial question: was environment the sole cause of my illness? My mother had her history with anorexia and bulimia during her university years, and other family members had struggled with addiction. Given the obsessive and controlling nature of anorexia, I began to consider the potential role of inherited factors. Could a genetic predisposition have made me more vulnerable to developing anorexia compared to someone facing similar environmental pressures? This is a key question in understanding the complex interplay of genetic and environmental factors in the development of anorexia nervosa.
Driven by this question, I delved into the scientific literature, seeking to unravel the intricate genetic underpinnings of anorexia nervosa. This exploration unveiled a complex landscape where both nature and nurture intertwine to shape an individual's susceptibility to this disorder, a fascinating puzzle that continues to captivate researchers and readers alike.
Research has firmly established a significant genetic component in eating disorders, particularly anorexia nervosa (Bulik et al., 2022). While early candidate gene studies yielded inconsistent results, linkage analyses identified promising chromosomal regions (1p36.13–1p34.2 and 1q25–1q41) that potentially harbour risk loci. Subsequent studies suggested candidate genes, such as OPRD1 and HTR1D, with the association for OPRD1 being replicated. Although genome-wide association studies (GWAS) were still in their early stages at the time of this review, they underscored the need for larger sample sizes to pinpoint specific genetic variants. Epigenetic research further revealed alterations in DNA methylation patterns in women with anorexia nervosa, potentially linking to increased anxiety and reward dysfunction often observed in the disorder (Bulik et al., 2022).
More recent investigations have delved deeper into epigenetic modifications in anorexia nervosa patients (Käver et al., 2024). These studies not only shed light on the disease's complexity but also offer hope for recovery. They suggest that epigenetic changes associated with malnutrition may be reversible with recovery and that DNA methylation levels could serve as biomarkers. This promising research, along with ongoing studies, fuels optimism for better treatments and outcomes.
Further evidence for a genetic basis comes from studies examining the overlap between anorexia nervosa and other traits. A study using GWAS data identified significant polygenic overlap between anorexia nervosa and body mass index, as well as anorexia nervosa and age at menarche, revealing shared genetic risk loci (Termorshuizen et al., 2025). This suggests that genes influencing anorexia nervosa may also play a role in regulating body weight and sexual maturation. The study also found evidence suggesting that genetic variants associated with anorexia nervosa may have been under recent positive evolutionary selection in humans, potentially linking the disorder to evolutionary pressures related to energy metabolism and reproductive functions. Genes related to circadian rhythms, such as ARNTL, were implicated. This genetic overlap has significant implications for our understanding of anorexia nervosa and its broader impact on human evolution and health.
Neurotransmitter systems, particularly serotonin, have also been implicated in anorexia nervosa. A meta-analysis of serotonin receptor gene polymorphisms found a small but significant association between the 5-HTR2A rs6311 polymorphism and anorexia nervosa, particularly in Southern European populations, suggesting a context-dependent genetic influence (Bevilacqua et al., 2024). However, no significant association was found for the 5-HTR2C rs6318 polymorphism. Another systematic review highlighted the role of the dopaminergic system, with polymorphisms in DRD2 linked to a predisposition for anorexia nervosa through mechanisms affecting perfectionism and stress response. The DRD3 gene and DAT1 gene were also associated with specific anorexia nervosa symptoms and traits. Additionally, the BDNF gene and other genes, such as OXTR, as well as the interaction between TFAP2B and KCTD15, have been implicated in various neurobiological and psychological factors relevant to anorexia nervosa (Almaghrbi & Bawadi, 2024).
Twin studies provide compelling evidence for the interplay of genetics and environment. Research on identical twin pairs discordant for anorexia nervosa and other specified feeding or eating disorders (OSFED) highlights that even with similar genetic makeup, differing environmental exposures, such as trauma, stress, health beliefs, and body ideals, can lead to divergent outcomes (Elwyn et al., 2024). These studies underscore the crucial role of individual experiences in the development of eating disorders. An extensive Danish population study further demonstrated significant interactions between genetic predisposition for anorexia nervosa and various birth-related, somatic, and psychosocial risk factors, suggesting that the impact of gene liability can be amplified or mitigated by environmental influences (Papini et al., 2024).
The ethical implications of genetic research in anorexia nervosa are also being considered. Concerns about equitable access to genetic testing and the need for increased genetic literacy among healthcare professionals are crucial as the field of genetics continues to evolve (Pinheiro et al., 2009). Research focusing on severe and enduring anorexia nervosa (SE-AN) emphasises the need to include this often-overlooked subgroup in genetic studies to gain a more comprehensive understanding of the disorder's etiology (Ramsay et al., 2024). Emerging research into microRNAs (miRNAs) offers another potential avenue for understanding the complex regulatory mechanisms involved in anorexia nervosa (Voelz et al., 2024), while a meta-analysis found no association between the serotonin transporter gene 5-HTTLPR polymorphism and anorexia nervosa in European populations, suggesting a shift towards more comprehensive genetic approaches (Brustolin et al., 2015).
Interestingly, unexpected environmental factors, such as exposure to delicate particulate matter (PM10), have been suggested as potential risk factors for anorexia nervosa in a Mendelian Randomization study (Tsitsi & Marouli, 2024), highlighting the potential for seemingly unrelated environmental influences. Furthermore, research has identified a bidirectional association between anorexia nervosa and morning chronotype, as well as a link between insomnia and increased risk, underscoring the role of circadian rhythms and sleep in the disorder (Wilcox et al., 2024). Studies on potential expression biomarkers have identified genes like VNN1 as downregulated in anorexia nervosa patients, possibly indicating an abnormal adaptive response to food restriction (Verebi et al., 2024). Research on risk factors for hospitalization in children and adolescents with anorexia nervosa indicates that lower BMI and a higher number of predisposing factors, including family history, life stress, and psychiatric comorbidities, increase the likelihood of severe outcomes (Benini et al., 2025).
Cutting-edge multi-omics research further illuminates the intricate interplay of biological factors, suggesting that disruptions in the gut-brain axis, specific metabolites, cholesterol levels, and the immune system may play a significant role in anorexia nervosa (Li & Bi, 2024). Additionally, recent genetic studies have provided novel insights into the shared and distinct genetic underpinnings of anorexia nervosa and binge eating (Termorshuizen et al., 2025), and unexpectedly identified obesity-associated gene mutations in individuals with anorexia nervosa, suggesting a more complex role for these genes in eating disorders (Rajcsanyi et al., 2024). The potential involvement of human endogenous retroviruses (HERVs) in anorexia nervosa, with altered expression levels observed in adolescents with the disorder, adds another layer of complexity to our understanding (Amianto et al., 2024). Finally, research continues to explore the specific psychological and environmental risk factors that contribute to the development and severity of anorexia nervosa (Dang et al., 2024).
Embracing the Complexity of Recovery
My journey through the scientific literature has profoundly reshaped my understanding of my own experience with anorexia nervosa. It is no longer solely a narrative of environmental triggers and personal struggles, but one interwoven with the threads of genetics and complex biological processes. While the environmental factors that precipitated my illness remain clear, the growing body of research suggests that a genetic predisposition may have heightened my vulnerability.
This understanding is not about assigning blame or diminishing the impact of my experiences. Instead, it offers a more comprehensive framework for comprehending the multifaceted nature of anorexia nervosa. It underscores that recovery is not simply about behavioural changes but also about acknowledging and addressing potential underlying biological vulnerabilities. The research also highlights the critical importance of early intervention and prevention strategies that consider both genetic and environmental risk factors.
The ongoing efforts to identify biomarkers, understand epigenetic changes, and explore the complex interplay of various biological systems offer hope for more targeted and effective treatments in the future. Recognizing the significant genetic component of anorexia nervosa can also help to destigmatize the disorder, fostering greater empathy and understanding. As research continues to unravel the intricate web of nature and nurture in anorexia nervosa, we move closer to a more compassionate, informed, and ultimately more effective approach to supporting individuals on their journey to recovery.
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