Single cases have provided clues to aid other serious diseases
Are there any examples of major medical breakthroughs arising from finding and studying just one patient? Yes, but these situations are uncommon, and require both scientific curiosity and, perhaps, an element of luck. Four examples will illustrate this.
Leukemia. The “Philadelphia chromosome”, which stimulated research into the roles of genes in leukemia, was identified in one patient in 1959:
HIV resistance. Another example is the ability of certain white cells to resist invasion by HIV. This retrovirus was discovered in 1983. But it took 24 years, until 2007, to recognize and study the first patient whose new white cells, arising from a donor’s bone marrow, were genetically able to bar entrance of the retrovirus. This effectively brought his HIV infection under control. He was labeled “the Berlin patient”, and his case stimulated research worldwide.
Jessen H, Allen TM, Streeck H (February 2014). “How a single patient influenced HIV research – 15-year follow-up”. The New England Journal of Medicine. 370 (7): 682–83. doi:10.1056/NEJMc1308413
It then took twelve years more, until 2019, for a second such individual to be discovered, in England. He was labeled “the London patient.”
Nature 568:244–248 (2019) https://www.nature.com/articles/s41586-019-1027-4 https://www.nature.com/articles/d41586-019-00798-3
Cancer defense. An early-career encounter, in 1968, with a man whose previously noted cancer metastases had unexpectedly disappeared without treatment, i.e. spontaneously, inspired Dr. Steven Rosenberg’s decades of investigation of the body’s ability to cure itself. Today, he is a leading researcher on immunological treatment of cancer at the National Cancer Institute, and its chief cancer surgeon.
IgG4-related disease. Haven’t heard of this? Don’t worry. Nobody else had either in 2008, when a woman from Casablanca walked into Massachusetts General Hospital seeking help for a swelling in her neck. Study led to the revelation of this disease, whereupon “patients came out of the woodwork”.