Cyclopamine

Cyclopamine: steroidal alkaloid.

Named after being discovered as the compound in wild corn lilies, that caused the offspring of sheep who had eaten it to have little cyclone-baby-sheep (aka cyclopia).

Its a teratogen (external agent that can harm a developing embryo/fetus) that messes with the "sonic hedgehog signalling pathway"
(yes, there is a protein named sonic hedgehog and i am such a geek that this makes me giggle as I'm a former Sega player)

Basically it turns "off" a signalling pathway, that leads to the transcription of certain genes, that needs to occur during normal development.

This pathway can also become messed up naturally, without cyclopamine, although rarely, and leads to holoprosencephaly; where the cerebral hemispheres of the brain fail to divide.

I was looking up pictures and i guess there was a case in India last year where a little baby was born with cyclopia. They think it might be due to the mother being exposed to cyclopamine.

Cyclopamine is being investigated for it's potential use in anti-cancer treatment. I guess the drug regulations in India are pretty lax and there's a low barrier of entry for human drug trials; meaning they smack advertisements on the back of buses singing the virtues of whatever drug and uninformed people routinely become guinea pigs.

As of the date of the article i stumbled upon, they still weren't sure how the mother had been exposed to the drug, but she had gotten some unknown treatments at a fertility clinic.