@lgb55 MGUS is considered asymptomatic, although neuropathy can be associated. My MGUS was detected 10 years ago following my polyneuropathy diagnosis (although I suspect is is more tied to my Celiac Disease because it hasn't worsened on a GF diet). If someone has a pre-existing condition it could potentially worsen it. I didn't get fatigue symptoms until after mine progressed to SMM two years ago, and likely because I already had chronic kidney disease. The sticky kappa proteins were high enough concentration to hit my kidneys. Here is one source on symptoms: https://uamshealth.com/condition/monoclonal-gammopathy-of-unknown-significance/

@lgb55 I think this might be what that doc was referring to. https://ashpublications.org/ashclinicalnews/news/6475/National-Cohort-Study-Suggests-MGUS-Increases-Risk