Just a small fraction of our 20,000 genes can cause disease when disrupted – yet that sliver accounts for thousands of rare disorders. The difficulty is: what can a doctor do to treat them? In a common condition such as type 2 diabetes, the underlying biology is similar for millions of patients. The doctor can prescribe metformin. But with a genetic disorder, the mutation might only affect a small number of people worldwide. In many cases, doctors won’t even know which mutation is responsible, let alone how to fix it.
Novel gene-editing breakthroughs are making headlines. But therapies are expensive and complex to develop. The cost of bringing any new drug to patients is now around $2bn, in part because, as Brian David Smith notes in New Drugs, Fair Prices, the “success rate, from discovery to market, is tiny” and there are approved treatments for “less than 10% of the 8,000 diseases that affect humans”. Commercial incentives, he argues, skew innovation towards lucrative cancer drugs and long-term treatments for large populations. Complex gene therapies for very rare conditions are seen as too costly to develop and too small to profit from.
