Each page covers one condition properly: what it actually is and what it feels like, what causes it, how common it really is and in whom, and how it's diagnosed — followed by the specific variants with a replicated link to it, and, where the research supports it, how genetics can change the way a medicine behaves.
Written in two registers so one page serves both readers: plain language first, then a clinical detail section with the precise terminology, effect sizes and diagnostic thresholds. Every claim is sourced from freely-available published research and cited on the page, so you can check us — or hand the page to your doctor. 385 conditions so far, growing continuously, and free to reuse with attribution (CC BY 4.0).
A reaction, not a disease: a medicine most people tolerate takes the skin off a few. The genome-wide scan found the risk in one place only — HLA — and the odds ratio among people who had taken allopurinol was 7.77.
Read more → EndocrineA condition defined by a committee, with no single test — and the genetics still found something. The strongest locus reached an odds ratio of 0.67, which for a common variant is large.
Read more → NeurologicalNot a bad headache. The two loci that replicated in migraine without aura point at neurons and at blood vessel walls — which is the century-old argument about what migraine is, showing up in the data.
Read more → AutoimmuneCrohn’s disease and ulcerative colitis are diagnosed separately, treated differently and inherited almost identically. Of the 163 positions found for inflammatory bowel disease, most contribute to both.
Read more → MetabolicTwo genes do most of the inherited work here, and both of them are plumbing: one moves urate out through the kidney, the other out through the gut. Neither is a reason to test, and one of them is a reason to be careful with a drug.
Read more → RespiratoryThe largest study of its kind found that childhood asthma and adult asthma do not have the same genetics — and that the allergy marker doctors have measured for decades is largely beside the point.
Read more → BehaviouralThe clearest published answer to "how many genes?" for any psychiatric condition: about 8,300 of them, together explaining at least a third of the liability. Which is also why no single one of the fourteen on this page tells you anything.
Read more → NeurologicalSix of these positions shift the odds slightly and mean nothing on their own. The seventh is different in kind, and it is the reason this page spends more space on what a result cannot tell you than on what it can.
Read more → BehaviouralOne of the clearest demonstrations of a rule that governs all of this: the more people they looked at, the smaller the effect got. It started at 1.31 and finished at 1.17 — and the second number is the honest one.
Read more → MusculoskeletalFor a century this was "wear and tear" — a joint used until it wore out. Then a scan of 4,800 people found its strongest signal in the immune genes, which is not where wear and tear lives.
Read more → RespiratoryHow well a pair of lungs works is heritable and measurable, and it is also mostly the result of what has been breathed. Both halves are true, and the second one is larger.
Read more → AutoimmuneFound twice, in two populations, with almost nothing in common between the answers. That is the finding — and it is a lesson about what "the genetics of a disease" means when the disease was only studied in one place.
Read more → AutoimmuneOne of the few conditions where the genetics led straight to the medicine. The pathways the 2009 scan implicated — IL-23 and NF-κB — are the pathways the drugs that changed psoriasis treatment now block.
Read more → CardiovascularCRP is one of the best predictors of cardiovascular events in the blood, and the genetics is the reason we know it is not a cause. Variants that raise CRP for life do not raise heart disease — which is exactly the test a marker has to fail to be demoted from a cause.
Read more → TraitThe largest study of how long people live looked at a million parents. What came out top was not a repair gene or a telomere gene — it was Alzheimer's risk, then smoking, then cholesterol, then heart disease, then blood pressure. There is no longevity gene in the results. There are disease genes, and not dying of those things is most of what a long life is.
Read more → BehaviouralOne of the most heritable common conditions there is — and one of the least predictable from a genome. Twin studies put the inherited share around 70-80%, yet the first reliable common variants were only found in 2019, and each one moves the odds by a few percent. This page is about why both of those are true at the same time.
Read more → AutoimmuneAn immune attack on the insulation around nerve fibres. One region — the MHC — carries by far the largest inherited effect, and everything else, including the variant here, is part of a long tail of small ones.
Read more → AutoimmuneAn autoimmune disease that attacks the lining of joints. The variant here sits in a small stretch of chromosome 6 that turned out to hold two independent signals 3.8 kb apart — a good picture of what it takes to say a region matters twice.
Read more → CancerAn odds ratio of 2.55 for one common variant — several times anything on this site's other cancer pages. Testicular cancer is unusual twice over: it strikes young men, and its common genetics is unusually strong.
Read more → CancerSmoking causes most bladder cancer, and blood in the urine is the symptom that matters. The variant here is unusual in a small way: it destroys a start codon, so what it does to the protein can be seen rather than guessed.
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One diagnosed condition or measurable trait covered properly: what it actually is, what causes it, how common it is, how it is diagnosed, and the specific variants with a replicated link to it — every claim sourced from published research.
No. Every page here is informational, not a diagnosis. A result should be discussed with a doctor or a licensed genetic counselor, never acted on alone.
Because they are not disorders. Height, ABO blood group and a handful of others describe a measurable characteristic with nothing to diagnose — "Trait" says so plainly instead of implying a disease that is not one.
Only after a replicated association in published research, verified against the primary study rather than a gene name or a marketing claim — the same discipline the variant pages themselves follow.