Fatal opioid overdoses typically result from a decrease in respiration and greater amounts of pFF in the medulla could lead to enhanced MOR activation resulting in an increased potential for respiratory depression and, therefore, a greater potential for fatal overdose (Baertsch et al. 2021; Pattinson 2008; Saunders et al. 2022). Here, OPRM1 is linked to Respiratory insufficiency due to muscle weakness.