Sickle cell disease is a single-gene disorder that affects hemoglobin, the oxygen-carrying molecule in red blood cells. A single mutation causes hemoglobin molecules to polymerize under certain conditions, deforming red cells into rigid, crescent shapes that lodge in small blood vessels. The consequences are cascading: vaso-occlusion triggers episodes of excruciating pain, chronic hemolytic anemia, inflammation, and progressive damage to organs including the kidneys, lungs, brain, and spleen. The disease is among the costliest chronic conditions in medicine, measured in both direct health care expenditure and lost human potential, and it disproportionately affects people of African, Mediterranean, Middle Eastern, and South Asian ancestry. Yet for all its molecular simplicity—one gene, one known mutation—the disease behaves with bewildering variability. Some patients endure frequent crises and early organ failure while others, carrying the same genotype, live comparatively well for decades. The reason for this divergence has remained one of the field’s most stubborn mysteries.

The Mount Sinai team, led by principal investigator Sarah McCuskee, MD, Assistant Professor of Emergency Medicine and of Global Health and Health Systems Design, believes the answer may lie substantially outside the genome—in the “exposome,” the cumulative measure of every environmental exposure an individual encounters from moment to moment across a lifetime. “We have heard time and time again from our patients: their lives impact their disease, and vice versa,” Dr. McCuskee said in announcing the award. “But until now, how daily life impacts sickle cell disease hasn’t been studied very much. We are excited to partner with people living with sickle cell disease to understand this better, while applying rigorous scientific methods to make sure our conclusions are impactful.” Her framing captures the project’s central ambition: to treat patient experience not as anecdote but as a valid signal that can be rigorously quantified, measured, and validated.

The biological logic behind the hypothesis is grounded in what preliminary work has already hinted at. Neighborhood and personal exposures are known to activate inflammatory pathways, alter vascular tone, and shift metabolic states—all processes directly implicated in sickle cell pathogenesis. Chronic psychosocial stress elevates cortisol and sympathetic nervous system activity, which can promote vasoconstriction and heighten the likelihood of vaso-occlusive events. Elevated ambient temperature is suspected of influencing blood viscosity and dehydration status, both critical variables in a disease where red cells sickle more readily when blood flow slows or plasma volume falls. Airborne particulate matter, particularly fine particles smaller than 2.5 micrometers, known as PM2.5, penetrates deep into the lungs and drives systemic inflammation through oxidative stress, an especially concerning mechanism for patients whose vasculature is already prone to inflammatory damage. Poor access to nutritious food may compromise the antioxidant defenses and hydration status that help keep sickling episodes at bay. Substandard housing—with inadequate heating, cooling, ventilation, or pest exposure—compounds all of these risks simultaneously.

The new study is among the first prospective investigations of exposures in sickle cell disease ever undertaken, and its methodology reflects the sophistication that such a claim demands. The researchers will pursue two complementary strategies. The first links blood samples previously donated by people with sickle cell disease for research to geospatial data on the exposures those individuals experience, drawing on advanced satellite-based models. These models can estimate ambient concentrations of fine particulate matter, neighborhood-level temperatures, and other environmental variables at fine resolution, allowing investigators to connect each participant’s residential history with molecular readouts of their disease state. The second strategy moves into real time: participants will carry portable air-quality sensors that directly measure the particles they breathe, and they will report on diet and stress levels as they occur. These moment-to-moment exposure data will then be linked to measurements of the body’s energy metabolism and inflammatory markers, giving researchers a dynamic picture of how a specific exposure on a specific day translates into molecular changes in the blood.

This pairing of satellite modeling and personal sensing is methodologically significant. Satellite data offers population-scale coverage and historical depth, but it estimates exposure at the ambient level and can miss what individuals actually encounter indoors, in transit, or in microenvironments like subway platforms and workplaces. Portable sensors capture the true inhaled dose but are limited in duration and cohort size. By triangulating the two approaches and anchoring both to biochemical endpoints—energy metabolism and inflammation—the study can distinguish between exposures that merely correlate with disease activity and those that plausibly drive it. If, for example, a spike in personally measured PM2.5 is followed within days by a rise in inflammatory cytokines and markers of hemolysis, the causal chain becomes far harder to dismiss. That kind of evidence, replicated across participants and seasons, is what regulatory policy and clinical guidance ultimately require.

The collaborative architecture of the project is equally deliberate. The research will be conducted in partnership with the Human Immune Monitoring Center at Mount Sinai, which provides deep immunophenotyping capability; the Institute for Exposomic Research at the Icahn School of Medicine, one of the first institutions in the world organized specifically around exposomic science; and the Center for Sickle Cell Disease, which anchors the clinical and community dimensions of the work. Exposomics—the systematic study of non-genetic drivers of health—has gained momentum in cancer, cardiovascular disease, and neurology, but its application to a monogenic disease like sickle cell is comparatively novel and potentially transformative, because it addresses the variability that the gene itself cannot explain.

Community partnership is not an afterthought in this design but a stated structural principle. When the study concludes, the researchers intend to share results widely, including through publicly available maps of neighborhood exposures co-developed with the New York City sickle cell community. That commitment matters for a disease whose patients have historically faced well-documented barriers in health care—under-treatment of pain, delayed emergency care, and skepticism about the severity of their symptoms. By giving the community access to the same exposure data that researchers use, the project aims to convert an academic finding into an advocacy tool, one that residents, clinicians, and policymakers can use to argue for cooler housing, cleaner air, and better food environments in the neighborhoods where sickle cell patients live.

The translational endpoint is clinical. Dr. McCuskee and her colleagues plan to develop tools based on their findings that will help clinicians counsel patients concretely—not in vague exhortations to “stay healthy,” but with specific, evidence-based guidance about which environmental conditions appear to elevate risk for a given individual, and what mitigations may help. Beyond sickle cell disease, the investigators hope the methods themselves—linking personal sensing, geospatial modeling, and molecular biomarkers—could form a template for investigating other chronic and genetic illnesses in which outcomes vary inexplicably from patient to patient, including cystic fibrosis, certain autoimmune conditions, and cardiovascular disease.

The grant will be distributed over five years, a duration long enough to capture seasonal variation in temperature, air quality, and stress exposures, and to observe whether exposure-driven molecular changes translate into clinical events such as pain crises, emergency department visits, or hospitalizations. If the study delivers on its promise, it could mark a turning point in how medicine understands a disease long defined by its genetics. The mutation in the hemoglobin gene has been known since the middle of the twentieth century; the environmental and social conditions that determine how severely that mutation expresses itself have, by comparison, barely been examined. Mount Sinai’s new program sets out to close that gap, grounded in the conviction that where people live is not background noise to their biology but part of it—and that understanding the two together may finally explain why one gene can produce so many different lives.