If you have 3 other plants going that are the same strain and in the exact same environment and are doing just fine, chances are this is just a genetic deformation (that's also what it visually appears to be as well). Nothing you can really do about it. You can choose to keep it, sometimes they can grow out of it and turn into a healthy normal plant, but more often then not they end up dying. But before you decide to pull it, I'd raise my lights a little or at least set that one a little further away from the rest to see if that help. Though I don't believe it is your light, but just for giggles and shits, what exact light do you have.

I know this light isn't much but it will only be used for seedlings this spring and they will be going outside when ready. It is a different strain than other ones.