What is inclusion body myositis?

Inclusion Body Myositis (IBM) is a rare, progressive muscle disease characterized by chronic muscle inflammation and weakness. It is the most common acquired muscle disease in adults over 50, affecting approximately 20,000 people in the United States.

Sporadic IBM (sIBM), the most common form, is NOT inherited — it occurs randomly. However, about 67% of patients carry a specific HLA gene combination that makes them genetically susceptible. Hereditary Inclusion Body Myopathies (hIBM) are a separate group of genetic muscle diseases.

Is there a cure for IBM?

As of 2026, there are no FDA-approved treatments specifically for IBM. The disease is notoriously resistant to corticosteroids and immunosuppressive drugs. Physical therapy and adaptive strategies are the mainstay of management. Active research is underway with promising clinical trials.

Does IBM qualify for disability benefits?

Yes. IBM is listed under Section 11.15 (Disorders of the Peripheral Nervous System) in the SSA Blue Book for Social Security Disability Insurance (SSDI). The IBM Functional Rating Scale can support your application.

What exercises are safe with IBM?

Walking, aquatic therapy, light resistance training, balance training, and hand/finger exercises are all recommended for IBM patients. Start slowly, build over 6-12 weeks, and consult with a physical therapist who understands myositis.

Why is IBM often misdiagnosed?

IBM is frequently misdiagnosed as polymyositis, normal aging, fibromyalgia, ALS, or sarcopenia. The average diagnostic delay is 5-10 years from symptom onset because IBM shares symptoms with more common conditions.

Gene Therapy Shows Promise in Mouse Model of Hereditary IBM

A study published July 9, 2026 in Human Gene Therapy reports early-stage results of a gene therapy approach for hereditary inclusion body myositis (hIBM) — a rare, genetically-caused form of IBM caused by mutations in the VCP gene.

What the Researchers Did

The team at Nationwide Children's Hospital, led by Dr. Zarife Sahenk, used an adeno-associated virus (AAV) called AAVrh74 to deliver a human gene called BAG3 into the muscles of VCP-A232E mice — a mouse model that mimics key features of hereditary IBM, including protein aggregates and mitochondrial abnormalities.

BAG3 is a protein that helps initiate the autophagy-lysosome pathway (ALP) — the cell's system for cleaning up misfolded proteins and damaged mitochondria. In hIBM, this cleanup system is overwhelmed, leading to toxic protein buildup and mitochondrial dysfunction. The idea behind the therapy is to boost the cell's cleaning capacity by delivering extra BAG3.

The mice received the gene therapy at 3 months of age and were evaluated 9 months later.

What They Found

The treated mice showed several improvements compared to untreated mice:

• Treadmill running distance improved — treated mice could run farther

• Rotarod duration improved — treated mice could balance on a rotating rod longer

• TDP-43-positive aggregates were reduced — these are the toxic protein clumps characteristic of hIBM

• Mitochondrial enzyme abnormalities decreased — fewer muscle fibers showed signs of damaged mitochondria

The therapy also increased levels of mitophagy markers (Parkin and Bnip3), a mitochondrial biogenesis marker (Pgc1-alpha), and mitochondrial DNA-encoded subunits of complex IV (Cox1 and Cox3). The LC-II/I ratio increased, indicating increased autophagic flux — meaning the cell's cleanup system was working harder.

Important Caveats

This is a preclinical study conducted in mice, not humans. Mouse models do not perfectly replicate human disease, and many treatments that work in mice fail in human trials. The gene therapy was delivered systemically (through the bloodstream), which raises questions about delivery, dosing, and safety that would need to be addressed in human studies.

This research is also specific to hereditary IBM caused by VCP mutations, which represents a small subset of all IBM cases. The majority of IBM is sporadic (not inherited), and it is not yet clear whether this approach would apply to sporadic IBM.

What This Means

The study provides proof-of-concept evidence that boosting the autophagy-lysosome pathway through BAG3 overexpression could be a viable therapeutic strategy for myodegenerative conditions associated with abnormal protein aggregates and mitochondrial dysfunction. However, human clinical trials would be needed to determine whether this approach is safe and effective in people.

For patients with hereditary IBM (VCP mutations), this represents one of several gene therapy approaches being explored. For patients with sporadic IBM, the findings add to the growing understanding of the biological pathways involved in the disease, which may inform future treatment development.

Source

• Ozes B, Tong L, Myers M, Moss K, Son E, Vetter TA, Vasquez-Martinez G, Zepeda-Orozco D, Sahenk Z. "AAV.hBAG3 Gene Therapy Improves Phenotype in a Valosin Containing Protein Mouse Model of Hereditary Inclusion Body Myositis." Human Gene Therapy. 2026 Jul 9. doi: 10.1177/10430342261466685. PMID: 42423109.