In Memoriam Peter James Dyck, MD

Peter James Dyck, MD, Professor of Neurology emeritus, the former Roy E. and Merle Meyer Professor of Neuroscience, and a true icon in the field of peripheral nerve disorders, died on July 26, 2025, at 97 years of age. Dr Dyck retired on December 31, 2024, after 63 years as a distinguished member of the Staff at the Mayo Clinic and was recognized as the longest-serving member of the Mayo Clinic Staff since its founding over 160 years ago. Despite retirement, he continued to write, propose new studies, and mentor us until shortly before his death. Dr Dyck was born in a small Mennonite village, Neue Hoffnung (New Hope), in the Southern USSR on October 20, 1927. He emigrated to Saskatchewan, Canada, with his family as a young child. He received his BA from the University of Saskatchewan in 1950, where he spent 3 years leading limnology studies on glacial Lac La Ronge, forming his fundamental, life-long approaches to scientific research. He completed the first two pre-clinic years of medical school at the University of Saskatchewan and received the MD from the University of Toronto in 1955. After Neurology and Neuropathology training at University Hospital, Saskatoon, he completed a fellowship in Neurology at the Mayo Clinic, where he had the opportunity to train with Edward Lambert and Donald Mulder. On July 1, 1961, he was appointed to the staff of the Mayo Clinic and became a full Professor of Neurology in 1973. Dr Dyck was a preeminent clinical investigator and served as a role model for all who chose that career path. Many of us were attracted to Peter because of his indefatigable curiosity, insatiable inquisitiveness, unending search for truth, and his persistence in whatever he was doing. He was never satisfied with the status quo, always asking questions and continually seeking answers to his patients' problems. He rarely spoke in statements but was more inclined to speak in questions of why, what, and how. The questions raised by the problems of his patients inspired his research for his entire career and inspired all who worked with him to pursue clinical investigation. Not only did he question himself, but he was also not hesitant to ask questions of others. A call from Peter early on a Saturday morning with a question about what he was working on was not unusual and, in fact, expected. I (WJL) miss those phone calls, the questions, and the conversations. Dr Dyck established the Mayo Clinic Peripheral Nerve Laboratory early in his career, initially focusing on the quantification of peripheral nerve attributes in healthy people and those with disease. Throughout his career, he continued to develop tools and methodologies to identify and characterize disorders of peripheral nerve and eventually used these tools to measure the changes in normal and diseased nerves over time. These tools were used in several clinical trials, initially in chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), then diabetic sensory motor peripheral neuropathy, and most recently in trials studying hATTR hereditary peripheral neuropathy. In the most recent trials, mNIS+7 (a composite of several assessment tools) is used and is recognized as the standard approach for evaluating hATTR peripheral neuropathies. It is impossible to summarize the breadth and depth of Dr. Dyck's contributions to the understanding of peripheral nerve and peripheral nerve diseases. During his career, he described the clinical, electrophysiological, and pathological features of many peripheral nerve disorders. Among these is the first study he published as a member of the Mayo staff, a description and characterization of a local family with Charcot–Marie Tooth disease later identified as having a PMP22 mutation. He categorized Charcot–Marie–Tooth neuropathy into two forms, demyelinating (Type 1) and neuronal (Type 2). Dr Dyck studied demyelinating neuropathies and published the initial description of patients with chronic inflammatory neuropathy, later naming this chronic inflammatory demyelinating polyradiculoneuropathy (CIDP). He led a clinical trial for the treatment of CIDP, which contemporary colleagues believe was the first controlled treatment trial for a peripheral nerve disorder (and perhaps for any neurological condition). The epidemiological study on diabetic neuropathy in Olmsted County, Minnesota, describing the incidence, spectrum, and progression of diabetic sensory motor polyneuropathy over a nearly 20-year time period was a major focus of his investigative career. Arguably, the findings and publications from these studies remain some of the most important insights into diabetic peripheral neuropathy. Ironically, the last major recognition of Peter's work was of a 1993 paper as a Hallmark paper by NeuroDiab, and this came shortly before his death. The emphasis of his last years was the study of amyloid peripheral neuropathy, specifically hATTR-PN. After characterizing the neuropathy, the tools he developed for assessing nerve changes over time have been and are still being used in clinical trials assessing the efficacy of pharmaceutical interventions. In the 1980s and early 1990s when the techniques for identifying the genetic abnormality in a familial peripheral neuropathy were not straightforward or simple, Dr Dyck led several adventures across North America to visit and study families with a peripheral nerve disorder. The team of clinicians, electrophysiologists, phlebotomists, and others would travel and study all family members available. These trips were memorable for some of the harsh field-study environments we worked in, the people we met, and the demanding work for the studies. The 14-year-old son of one of us (WJL), after a day of study, exclaimed he would never be a neurologist because they get up before sunrise, work until dark, eat dinner, then go to bed. Certainly, an apt description of the work, but it was fun, and the results were remarkable. The genetic abnormality was identified in several families. Similar field studies were done on Native American reservations attempting to characterize peripheral neuropathy in an Indigenous Indian population. Dr Dyck's remarkable accomplishments in the field of peripheral neuropathy were recognized with numerous awards and honors including the Roy E. and Merle Meyer Professor of Neuroscience, the Mayo Clinic Distinguished Investigator Award (2004), Mayo Clinic Distinguished Alumnus Award (2007), and Teacher of the Year Award in the Department of Neurology (1996). He was honored to be the Wartenberg Lecturer at the American Academy of Neurology, the Robert S. Schwab Award from the American Clinical Neurophysiology Society in 2023, and received the Neurodiab Lifetime Achievement Award and the Albert Nelson Marquis Achievement Award. He is an Honorary Member of several organizations including the American Academy of Neurology, American Neurological Association, American Association of Neuromuscular and Electrodiagnostic Medicine, Canadian Society of Clinical Neurophysiologists, European Neurological Society, and the Mexican Neurological Association. Dr Dyck was a founding member of the Peripheral Nerve Study Group and the Peripheral Nerve Association. The merger of these two organizations created the present-day Peripheral Nerve Society (PNS). The PNS recognized Peter's contributions by starting the Peter J. Dyck lectureship. During his career, he served as President of the PNA and the American Neurological Association. Dr Dyck was a remarkable teacher whether it was sitting around the microscope discussing nerve biopsies, giving formal lectures, or simply through conversations at the lunch table with fellows and colleagues discussing current events, the arts, music, the latest book we were reading, or some aspect of peripheral neuropathy. Dr Dyck mentored ~150 international fellows in the field of peripheral neuropathy. He inspired and educated generations of healthcare professionals, many of whom have made major contributions to the understanding of peripheral nerve disorders. His legacy will live on in the outstanding clinical and pathological training he provided. Peter was a superb and fair but hard mentor and colleague. Because of his very high standards, he was a demanding person yet very encouraging and respectful of good work and strong ideas. Although Peter could be a harsh critic, he was quick to admit his own errors. Dr Dyck wrote over 460 peer-reviewed articles, 129 book chapters, and 27 reviews. He was the editor of four editions of Peripheral Neuropathy (Saunders/Elsevier), considered by many to be the standard textbook for peripheral nerve disease. Peter edited four other books on peripheral neuropathy. Dr Dyck was a gregarious and fun-loving man, some might say an eccentric, who loved and cared for his immediate and extended family. His wife of over 70 years, Isabelle, and Peter were close companions and shared so many interests, including art, literature, music, and lively political discussion. They always read together and, in later years, listened to audiobooks. He particularly loved music, and a JS Bach organ fugue would bring a smile to his face. Throughout his life, he provided major support to several music organizations that profited from his unending efforts. His four children, Ernie, Fred, P. James, and Kate, were an integral part of Peter's life. He spoke of them often and was proud of them and their accomplishments. Dr Peter J. Dyck will be missed. William J. Litchy: writing – original draft. P. James B. Dyck: writing – review and editing. The authors declare no conflicts of interest. Data sharing not applicable to this article as no datasets were generated or analyzed during the current study.

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