Yesterday, the US government approved a genetically modified chicken. Its purpose? To make a drug in its eggs.

The drug in question is called Kanuma, reports Nature. It's the first treatment approved for people with "lysosomal acid lipase deficiency" — a rare genetic condition that prevents the body from breaking down fatty molecules inside cells. Unlike the FDA's recent approval of genetically modified salmon, these chickens and their eggs aren't approved for human consumption.

Drugs in goat and rabbit milk

This isn't the first time that the FDA has approved a transgenic animal for drug production. Six years ago, the US government approved genetically modified goats that can make a drug in their milk that prevents blood clots. And in 2014, the FDA approved Ruconest — a drug that's collected from rabbit milk.

But yesterday's approval doesn't rely on milk production. To collect the active protein, researchers have to purify it from the whites of the chicken's eggs. Kanuma works by replacing a malfunctioning enzyme in people with lysosomal acid lipase deficiency.

As part of the approval process for the drug, the government officials looked at whether the alterations made to the chicken's genetic material would cause it harm. They also examined whether these changes are stable enough to be passed on to future generations.

Because these chickens are raised indoors, it's unlikely that these animals will accidentally end up in the food supply, the FDA says. The company that makes the drug "has taken rigorous steps to ensure that neither the chickens nor the eggs will enter the food supply," Bernadette Dunham, director of the FDA's Center for Veterinary Medicine, said in a press release. "And we have confirmed their containment systems by inspecting the manufacturing facilities."

Correction: A previous version of this article incorrectly stated that Bernadette Dunham is the director of the CDC's Center for Veterinary Medicine. In fact, she is the director of the FDA's Center for Veterinary Medicine. We regret the error.