New babcy chick missing feathers on one wing

[bawkybawk]

I have a baby chick who's probably about a week old who has full feathers on one wing but none on the other. What would cause this? It's the only one in a group of 5 chicks that seems to have this problem.

 

[bawkybawk]

Here's a couple of photos

 

[bawkybawk]

Update: it's a been weeks and the chick seems to be growing all her feathers in now. Slow start but looks like she might have a normal wing eventually.