Is there any other problems occurring with the foliage, such as yellowing or browning, leaf drop, powdery mildew, for example?
Are these plants kept indoors or outdoors? If outdoors, did they get cold or frozen - winter damage?
How often do you water your golden king hollies? Is it possible you are over-watering or under-watering them? The best way you can tell is by touch - if the soil is damp - you have overwatered. If it's dry to the touch - they need water.
Sometimes insects can cause leaf curl. I would inspect your hollies thoroughly for any kind of pest infestation such as scale, mites or caterpillars (holly bud moth). The following article will give you more details on pests:
Let's start with that...
For more information on the care of holly bushes, please visit the following link: