With decreases in renal glomerular filtration rate, there is a corresponding decrease in renal clearance of FLC, leading to a mild increase in the SFLC ratio in the absence of MG.13 A large number of patients with an abnormal SFLC ratio and no M-protein on SPE in our study cohort could be explained by renal impairment. Here, MYOM2 is linked to myasthenia gravis.