Exploring the genetic link between obstructive sleep apnea and obesity: A bidirectional Mendelian randomization study

Obstructive sleep apnea (OSA) and obesity are interrelated conditions with significant public health implications, but the genetic causal association between them remains unclear. This study investigates their bidirectional causality using Mendelian randomization (MR).

Genetic data for OSA were obtained from the FinnGen consortium, including 38,998 OSA cases and 336,659 controls, as well as a broader sleep-disorder phenotype comprising 44,299 cases and 329,251 controls. Genetic data for obesity-related traits were sourced from large-scale genome-wide association studies from the GIANT consortium, including body mass index (BMI; n = 681,275), waist-hip ratio (WHR; n = 224,459), and WHR adjusted for BMI (WHRadjBMI; n = 694,649). MR analyses were performed using inverse variance weighting (IVW) as the primary method, with weighted median and MR-Egger analyses for sensitivity assessment.

OSA was causally associated with increased BMI (IVW: OR = 1.275, 95 % CI = 1.070-1.520, p = 0.0065), trunk fat mass (IVW: OR = 1.323, 95 %CI = 1.166-1.501, p = 1.46e-05), and whole-body fat mass (IVW: OR = 1.327, 95 %CI = 1.164-1.512, p = 2.21e-05). Conversely, obesity measures such as BMI (IVW: OR = 1.929, 95 %CI = 1.808-2.059, p = 3.05e-87), trunk fat mass (IVW: OR = 1.630, 95 %CI = 1.515-1.753, p = 4.21e-39), and leg fat mass (IVW: OR = 1.959, 95 %CI = 1.796-2.137, p = 5.93e-52) were causally linked to OSA. No significant association was found between WHR or WHRadjBMI and OSA (p > 0.05).

This study provides genetic evidence of a bidirectional causal relationship between OSA and obesity, emphasizing the role of systemic and regional fat distribution. Integrated management strategies targeting weight reduction and OSA treatment may mitigate the mutual burden of these conditions.