Recent development of newer composite outcome measures such as progression independent of relapse activity (PIRA) and relapse-associated worsening has demonstrated that people with multiple sclerosis can progress through different underlying mechanisms.55 Along these lines, we emulated a similar proxy comparison in our study sample and showcased that people with multiple sclerosis that progressed without the presence of any relapse had significantly greater baseline NfL levels. The gene discussed is NEFL; the disease is multiple sclerosis.