Are my Potatoes Sick?

Shriveled top of plant

I have not taken the time to research this... but are my potatoes sick?  The leaves have curled way back, others looked really crinkly.  It's is only a couple plants.  Any one have any idea what is going on?  My first thought is some type of blight....I will research this more but any insight you might be able to provide would be welcome!

Crinkled leaf

Healthy leaf