Developing drugs for rare diseases has become a big business. But while the hype over lofty sales, soaring IPOs, and high-profile acquisitions has reached fever pitch, the reality is that millions of families affected by rare diseases are still desperate for treatments. The feature uses the stories of three families with children who have rare diseases to guide the reader through the business, government and patient forces surrounding rare disease drugs.

The story shows that patient advocacy groups are becoming increasingly savvy. They organize themselves, fund basic science and in some cases even pay for drug discovery and early clinical studies in hopes of attracting biotech and pharma companies to their disease. Although the perception is that rare diseases are universally attractive to drug companies, the story reveals that a large swath of the roughly 7,000 rare diseases don’t fit into industry’s business plan. The “ultra rare” diseases—the thousands of disorders affecting anywhere from a few to a few hundred people—are losing out in the rare disease frenzy.