Genetic Factors Shape Response to Weight-Loss Injections, Study Finds
An individual's genetic makeup could significantly influence the effectiveness of weight-loss injections, according to a groundbreaking new study. Researchers have discovered that specific gene variants can predict both the degree of weight loss achieved and an individual's likelihood of experiencing side effects like nausea and vomiting. This insight helps explain why some people lose weight more rapidly than others while using these medications, while others face greater vulnerability to adverse reactions.
Examining Genetic Data from Thousands of Users
The study, published in the prestigious journal Nature, analysed data from nearly 28,000 people registered with the genetics website 23andMe. Participants provided self-reported information on their use of GLP-1 receptor agonist weight-loss treatments, including semaglutide (marketed as Wegovy) and tirzepatide (known as Mounjaro). By examining genetic data, researchers identified variations in two genes involved with hormones in the gut that regulate appetite and digestion, which appear to play a crucial role in how these drugs function.
Key Genetic Variants Linked to Outcomes
One variant, known as rs10305420 in the GLP1 receptor gene, was associated with a slightly greater decrease in body mass index (BMI) among individuals taking GLP-1 drugs. Another variant, rs1800437 in the gastric inhibitory polypeptide receptor gene, was linked to side effects of nausea and vomiting in people using tirzepatide, though it did not correlate with the amount of weight lost. The research team, led by experts from 23andMe and The University of Copenhagen, suggested that these genetic differences may partially account for the variability in weight loss observed among users.
Modest Effects and Broader Context
However, the researchers emphasised that the genetic effects were "modest" and called for further studies to explore the role of genetics in these treatments more comprehensively. They noted that other non-genetic factors, including gender, age, and the specific treatment regimen, also play significant roles in determining outcomes. Dr Marie Spreckley, research programme manager at the University of Cambridge, commented on the findings, stating that the study "provides biologically plausible evidence that variation in the drug target itself and related pathways contributes to inter-individual variability in response."
Dr Spreckley added, "The magnitude of these genetic effects is small in clinical terms. Importantly, non-genetic factors such as sex, drug type, dose, and duration appear to explain a substantially larger proportion of variability." She further explained that while the research reinforces the idea of variability in response to GLP-1 therapies, genetics is only one component of a much more complex picture. Behavioural, clinical, and treatment-related factors remain the dominant drivers of outcomes, and the evidence is not yet sufficient to support using genetic information to guide treatment decisions in routine clinical practice.
Pathway to Precision Medicine
Despite the modest effects, the findings offer a promising pathway towards developing precision medicine approaches. This could eventually allow doctors to tailor weight-loss treatments based on individual genetic profiles, optimising efficacy and minimising side effects. The study represents an important step forward in understanding the variability in drug responses and highlights the potential for future personalised healthcare strategies in managing obesity and related conditions.
