Because the research looked for one marker in small, inconsistently defined samples for thirty years, and MCS is not a one-marker condition. The most important external development in the field is a rigorous evidence review now underway at the University of Southern California’s Evidence Review Center with Johns Hopkins. When it publishes, this site will report what it finds, whichever direction it points.
The Southern California Evidence Review Center is one of nine federally designated Evidence-based Practice Centers. It published a scoping-review protocol for MCS in 2023 and a systematic-review protocol in 2025, asking whether MCS is a distinct disorder, what mechanisms have empirical support, what diagnostic tools perform, and which treatments are effective and safe. The project is registered on the Open Science Framework.
The evidence map reportedly screened over twelve thousand citations and identified more than 350 eligible studies — over 200 on mechanism, dozens on diagnostic tests, around 60 on treatment — and characterized the treatment evidence as limited with few high-quality studies. Those counts come from conference reporting and are confirmed against the published review before this site cites them as fact.
What thirty years of that literature shows is a field that repeatedly found group differences — in receptors, in imaging, in cytokines, in genotypes — and never converted one into a test for an individual, because samples were small, definitions varied, and each lab measured its own favorite system. That is the biomarker problem, and it is a design problem, not evidence that nothing is there.
An independent, methodologically strict review grading the certainty of every conclusion is exactly what MCS has lacked. If it finds the biological evidence stronger than the psychological, the position on this site gains an authority it cannot give itself. If it finds the evidence weaker than this site claims, specific pages change. Either way it is incorporated, not selectively quoted.
Recording which objective findings participants already carry, so that when the review names the most promising markers the registry can test them in a characterized population.
No biomarker exists because the field never measured the right things in the right people together. The USC/Johns Hopkins review is the field’s first full accounting; we will report it straight.