In the biotech world, every now and then a moment comes along that can rewrite the rules of the industry. Most breakthrough attempts remain halfway - lack of data, complications in trials, unsustainable development models. But this time the situation is different. A small Dutch company has done something no other developer has managed: its experimental gene therapy has demonstrated a lasting biological effect on Huntington's disease, a fatal neurodegenerative disorder for which there is no approved treatment.

From a scientific perspective, this is a breakthrough; from a market perspective, it is an explosion of optimism. The company's shares jumped nearly 300% in a single day (after the announcement of the success) as investors began to appreciate not only the potential value of the therapy itself, but also the fact that gene therapy for brain disease is no longer a theoretical concept. Biotechnology, which for years has suffered from scepticism and losses, is suddenly the epicentre of…