When a heatwave causes a power cut, advice to move somewhere cooler or seek care elsewhere may sound straightforward. For someone who cannot sweat normally, depends on electrically powered ventilation or needs a medicine with no substitute, those alternatives may be unavailable. A disruption that others can manage could quickly become life-threatening.
In a Nature Climate Change commentary, Teguh Haryo Sasongko argues that people living with rare diseases are being overlooked in climate adaptation. His central concern is a “rarity penalty”: uncommon conditions can escape research, planning and emergency arrangements, even when the consequences of disrupted care are severe.
Rare diseases collectively affect an estimated 3.5–5.9% of the global population. Individually, however, many are exceptionally uncommon. This combination creates a challenge for health systems: a substantial population has needs spread across thousands of conditions, specialist services and treatment pathways.
Why conventional evidence can miss the risk
Climate and health research commonly looks for measurable associations between environmental exposures and outcomes across populations. These methods are essential, but they can struggle to detect risks affecting only a small number of people with a particular condition.
Some rare diseases already have recognised vulnerabilities to heat. Hypohidrotic ectodermal dysplasia, for example, can reduce or prevent sweating, making active cooling essential. Certain rare epilepsies and neurological conditions can also be sensitive to temperature.
The commentary highlights emerging evidence that some genetic variants have effects that vary with temperature. This raises questions about how warming could influence particular conditions, although the extent of these effects requires further investigation.
Information gaps compound the problem. Rare-disease records are scattered across specialist centres, laboratories, registries and patient organisations. They seldom systematically capture environmental exposures, disaster-related treatment interruptions or dependence on cooling and electricity. Climate and health datasets, meanwhile, often lack detailed information about rare conditions.
The result is a dangerous possibility: a risk that is difficult to measure may be treated as though it does not exist.
Broad vulnerability labels are not enough
Describing someone as having a chronic illness or being medically vulnerable does not tell emergency planners what they need to remain safe.
One person may require strict temperature control. Another may depend on refrigerated medicines, regular infusions, specialised nutrition or rapid access to a particular clinical team. Their needs differ, as does the time available before an interruption becomes dangerous.
Rare-disease care can also have very few alternatives. Expertise may be concentrated in one centre, a diagnostic service may rely on a single laboratory, or a specialised product may have only one supplier. These arrangements can work efficiently under normal conditions while creating critical weaknesses during extreme weather.
Climate preparedness needs to consider both how many people face a risk and what happens when an essential service fails
Sasongko cites evidence from all 24 European Reference Networks showing that only two of those networks reported pre-existing crisis-preparedness plans. This finding concerns crisis preparedness broadly, but illustrates gaps relevant to climate-related disruption.
Planning around consequences
The commentary proposes complementing population-level assessments with five practical questions:
- Risk: Could a climate hazard worsen the condition or interrupt essential care?
- Urgency: How quickly could serious harm occur?
- Substitutability: Is a clinically acceptable alternative available?
- Reachability: Can services contact the patient, and can the patient reach care?
- Responsibility: Who will organise and activate the necessary support?
Sasongko also proposes a patient-held “critical-function adaptation passport”, linked to clinical records. It would identify essential functions, how long interruptions could safely last, available alternatives and who is responsible for responding.This is a proposed approach, rather than a proven intervention, and requires field evaluation before full implementation.
The wider lesson extends beyond rare diseases to people dependent on dialysis, home ventilation, transplant medicines or geographically concentrated services. Climate preparedness needs to consider both how many people face a risk and what happens when an essential service fails. Families’ ability to improvise should not be mistaken for a resilient health system.
Source: Sasongko, T. H. Rare diseases are an overlooked dimension in climate–health adaptation. Nature Climate Change. Read the article.