Certified GKH Gardening Expert
This appears to be what is known as Witches' Broom Disease.
It has many causes, from fungal infections to insect infestations. There is no real cure, and it will usually resolve itself over time.
Here is an article that will explain:
You will want to care for the shrub as usual. Proper care will give it the best chance to come out of this. Here is an article that will help you care for the shrub: