The hedgehog gene was discovered in fly while studying mutants that altered development. The hedgehog mutant flies were named this because their hairlike denticles formed a thick lawn instead of the normal stripe pattern.
It has duplicated in vertebrates, with each type of hedgehog (sonic, indian, desert) taking on different developmental roles. Mutations in human indian hedgehog gene cause various skeletal problems.
Click here to see the sequence of Day 56 with your IHH gene underlined.