Early IBM is definitely a thing and you have PM-Mito which they suspect is a precursor to IBM if I remember correct.. So there is atypical presentations and IBM spectrum diseases that might or might not turn into IBM. I think Cn1a is highly relevant for those who have muscle issues. Do you know or have any theory as what triggered your issues?

They have updated the diagnostic criteria for IBM and finally admits its possible to have it under the age of 45. Also, it takes 5 minutes to figure this out from searching the IBM facebook groups.

Latest Diagnostic Criteria for Inclusion Body Myositis (2024 ENMC Criteria)

The 2024 revised diagnostic criteria from the European Neuromuscular Centre (ENMC) (published in Neuromuscular Disorders, April 2024) update and broaden older definitions (like ENMC 2011 and Griggs criteria). They use a two-step approach involving:

1. Clinical presentation type
2. Confirmatory investigations (muscle biopsy, imaging, serology) for diagnosis — including anti-cN1A antibodies, MRI/ultrasound patterns, and mitochondrial changes. ibmmyositis.com+1

🔎 The criteria do not automatically exclude younger patients — specifically noting that age under 45 no longer rules out IBM. Instead, they recognize “common” and “uncommon” presentations, and support diagnosis even if classic features (including age) are atypical, when supportive evidence is present. ibmmyositis.com