When it comes to expensive drugs, most people think of prohibitively pricey cancer treatments for which a month’s worth of meds can often cost more than a fancy sports car. But the average cancer patient is usually on such drugs for only a few months, so the annual tab rarely dips into the six digit range.

Drugs for rare genetic diseases, however, require around-the-calendar dosing. And with small target audiences and few if any alternative treatments, many biotech companies are left to charge whatever they want.

Here are the yearly price tags for the nine most expensive drugs, according to Forbes, most of which combat diseases that afflict fewer than 10,000 people around the world. (The number of patients reflects the disease prevalence — not the number of people taking the medication. All figures are for global incidence unless otherwise stated: * Europe and North America; ** US only.)

Click here to enlarge.