Associate Professor Karra Jones, MD, PhD collaborated in a multi-institutional effort to establish normal ranges for pediatric muscle fiber sizes. Her team’s findings, which will assist with clinical review and clinical trial assessments for pediatric patients with muscle diseases, were published in the in the December 2025 issue of the Journal of Neurology and Experimental Neuroscience (JNEN).
Doctors rely on the size of tiny structures inside our muscles called skeletal muscle fibers to help diagnose a wide range of muscle diseases. For children, the standard measurements used to judge whether these fibers are normal or abnormal were mostly created decades ago, in the 1970s and 1980s. Those early measurements were based on small sample sizes and often were measured by hand on photomicrographs of sections on slides, sometimes even from autopsy tissue.
Recognizing the need for more accurate and up‑to‑date information, a team of specialists from major universities and children’s hospitals joined forces to create new, modern standards. Using digital imaging tools, they analyzed muscle biopsies from pediatric patients to build a more reliable set of reference measurements for today’s clinical and research needs.
Jones had the opportunity to contribute to the data collection, analysis, and interpretation alongside colleagues Michael Lawlor, MD, PhD, (Medical College of Wisconsin and Diverge Translational Science Laboratory), Heather Dressman, PhD, (Children’s National Hospital, Washington, DC), Marta Margeta, MD, PhD, (University of California, San Francisco), and Benedikt Schoser, MD, (Ludwig‑Maximilians‑University Munich in Germany), among others.
Read the article and see a full list of authors here.
Jones is medical director for Outreach and Business Development and the Electron Microscopy and Immunochemistry Laboratory. In addition to her clinical and outreach work, she is the director of the Neuropathology Fellowship Program. She also serves as the section head for Muscle & Nerve Pathology.