The hedgehog genes play an important role in directing the development of body structures. They got their nickname because mutant forms of them cause fruit flies to grow up short and hairy. One of the most important of them, the Sonic hedgehog gene, got the rest of his name, in a bit of whimsy, from the video game character. Some clinicians are troubled by humorous or eccentric names. They worry that the frivolity will offend patients with serious illnesses caused by abnormalities in these genes.