The company reading brain health from a tube of blood - using the loop of RNA that biology nearly threw away.
Pictured: a logo for a molecule shaped like a circle, made by a company that bet the whole thing on a loop. On the nose, and they know it.
In a lab off Alexandria Way in San Diego, a small team is doing something that sounds like a magic trick and is actually molecular biology: they pull a vial of ordinary blood and read it for signals that started inside a living brain. No spinal tap. No PET scanner the size of a car. Just blood, and a class of molecule that most of genomics spent two decades ignoring.
That molecule is circular RNA - circRNA, if you want to sound like you belong in the room. It is RNA that folds back and joins its own tail, forming a closed loop with no loose ends. For years it was filed under "splicing error," the biological equivalent of a typo. Circular Genomics looked at the typo and saw a sentence.
Brain disorders should be measurable and manageable.- The premise the whole company rests on
The company is seventeen people, one $15 million Series A, and a stubbornly specific idea: that the brain leaves fingerprints in the bloodstream, and that circRNA is the ink. Today that idea is aimed at Alzheimer's disease and clinical depression. The ambition is larger - Parkinson's, multiple sclerosis, bipolar disorder, the whole difficult catalog of conditions we currently diagnose mostly by watching and waiting.
Cardiologists have troponin. Diabetologists have A1c. Cancer has a growing shelf of molecular tests. The brain, locked behind the blood-brain barrier, has resisted that kind of clean readout. For most of psychiatry and a good deal of neurology, diagnosis still leans on questionnaires, observation, and time.
Consider depression. First-line antidepressants fail roughly 60% of the time, and finding one that works can take about a year of trial and error. That is a year of a person's life spent as a guessing game. Alzheimer's is worse in a different way: by the time memory visibly slips, the underlying biology has often been running for a decade or more.
The honest problem is access. There are good biomarkers buried in spinal fluid and visible on expensive scans - but you cannot run a continent's worth of patients through a lumbar puncture. What was missing was something stable, brain-derived, and readable from a substance you can collect at any clinic on earth.
We can work to end the guessing game mental health patients currently have to go through.- Nikolaos Mellios, Co-Founder & Chief Scientific Officer
Nikolaos Mellios, MD, PhD, spent years as a tenured associate professor in the University of New Mexico's Department of Neurosciences, studying how circular RNAs help run the molecular networks behind psychiatric and neurological disease. Most people who study circRNA write papers about it. Mellios decided it should leave the journal and enter the clinic.
In 2021 he spun Circular Genomics out of the university - technology licensed, lab notebooks closed, company opened. The bet was not subtle. Pick the most overlooked RNA in the genome and build a diagnostics company on the precise properties everyone else had treated as a curiosity: that circRNAs are unusually stable because their closed loop has no ends for enzymes to chew on, that they are richly expressed in the brain, and that - critically - they can be detected in blood.
This technology provides a fundamentally different and more comprehensive view of Alzheimer's disease biology than existing biomarkers.- Joe Cook III, Mountain Group Partners
By the time the company raised its Series A in December 2025, CEO Paul Sargeant had joined to run the commercial and clinical engine while Mellios held the science. The split is the usual one - the scientist who saw the thing, and the operator brought in to make a continent of clinics actually order the test.
MD, PhD. Former tenured neuroscience professor at the University of New Mexico; the circRNA science is his life's work.
Leads clinical development, commercialization and the company's push from research result into ordered diagnostic test.
The core asset is a circRNA biomarker platform - a way to measure brain-enriched circular RNAs in whole blood and turn those measurements into clinical answers. From that single foundation, Circular Genomics is building tests pointed at different questions.
Detects brain-derived circular RNAs that cross the blood-brain barrier and stay measurable in a routine blood sample - the foundation under everything else.
Blood-based circRNA signatures designed to flag Alzheimer's biology at its earliest stages, potentially before memory and thinking issues appear.
A circRNA test to predict who will respond to SSRIs such as sertraline, aiming to replace trial-and-error prescribing. Built on the EMBARC study.
This Series A financing represents a pivotal milestone in our journey to transform precision neurology.- Paul Sargeant, Chief Executive Officer
What can a clinician actually do with it? Order a blood test, and instead of waiting for a year of failed prescriptions or a decade of quiet decline, get an early, actionable read. For a patient, that can mean the right antidepressant sooner, or a diagnosis caught while there is still time to plan. The business model is straightforward B2B diagnostics: tests delivered through CLIA laboratory workflows, with academic and pharmaceutical partners running validation in parallel.
Nikolaos Mellios licenses the circRNA technology and founds Circular Genomics to take it from the journal to the clinic.
Using the EMBARC study with UT Southwestern's Dr. Madhukar Trivedi, brain-enriched circRNAs in blood are shown to forecast sertraline response.
The company readies a circRNA-based therapy-selection service for delivery through a CLIA laboratory-developed test.
Circular Genomics unveils data positioning circRNAs as a transformative class of blood-based biomarkers for Alzheimer's disease.
Mountain Group Partners leads the round; Alzheimer's luminaries Michael Weiner and Timothy Hohman join the scientific advisory board.
Alliances with Vitazi.ai (multimodal Alzheimer's detection) and Decode Health (multiple sclerosis) extend the platform's reach.
Earlier rounds are inferred from total funding (~$31.2M) minus the disclosed $15M Series A; treat the first bar as approximate. Sources: company and press releases, Dec 2025.
The Series A was led by Mountain Group Partners, with Poplar Grove Investors, the HIP Fund, and - tellingly - the Alzheimer's Drug Discovery Foundation, a backer that does not write checks for science it doubts. The capital is earmarked for clinical validation across more diverse patient populations, platform expansion beyond Alzheimer's, and the unglamorous, decisive work of regulatory and commercial team-building.
Circular Genomics has assembled a scientific advisory board that reads like a guest list for an Alzheimer's research summit. The point of that roster is not decoration - it is the kind of validation that tells skeptical clinicians and regulators the science is worth a serious look.
UCSF professor emeritus; principal investigator of the landmark Alzheimer's Disease Neuroimaging Initiative (ADNI).
Washington University School of Medicine; a leading voice in Alzheimer's genomics.
Vanderbilt computational geneticist leading the biomarker core of its Memory & Alzheimer's Center.
The board also includes Roy Perlis (Mass General / Harvard), Madhukar Trivedi (UT Southwestern), Eleni Tzavara (CNRS), Henrik Zetterberg, and industry veterans Michael Ackermann and Phyllis Ferrell. On the partnership side, the company is working with Vitazi.ai on a multimodal Alzheimer's detection workflow and with Decode Health on multiple sclerosis biomarkers.
Their combined expertise in large-scale clinical trials, neuroimaging, and computational genomics is invaluable as we move to validate and commercialize our best-in-class circRNA blood-based biomarkers.- Nikolaos Mellios, Co-Founder & CSO
The stated mission is to make brain disorders measurable and manageable, so that treatment decisions stop being a polite form of guesswork. It is a deceptively modest sentence. Measurement is how every other branch of medicine grew up - you cannot manage what you cannot count.
Circular Genomics is wagering that circRNA becomes to brain health what cholesterol panels became to cardiology: a routine, low-friction number that quietly reorganizes how care happens. Start with Alzheimer's and depression because the need is loudest there. Expand into Parkinson's, multiple sclerosis and bipolar disorder because the platform, in principle, does not care which brain condition it is reading.
Picture the same clinic, a few years on. A patient in their late fifties comes in with nothing dramatic - a little forgetfulness, a mood that will not lift. Today that visit produces a referral and a wait. In the world Circular Genomics is building, it produces a blood draw, and a few days later, a number: a read on whether Alzheimer's biology is already underway, or whether a particular antidepressant is likely to work before the prescription is ever filled.
Actionable insights, potentially even before memory and thinking issues emerge, that can fundamentally change patient care trajectories.- Andrew Lechleiter, Poplar Grove Investors
That is the whole bet, returned to where it started: the blood draw that walks into a clinic and leaves knowing something. The molecule biology nearly discarded turns out to be one of the most stable, brain-faithful signals we have. Circular Genomics did not invent circRNA. It just refused to treat it as a typo - and is now trying to turn it into a sentence the entire field can read.