Can Chemical Relaxers Done Professionally and Correctly Still Cause Hair Loss?

Can chemical relaxers applied properly by a professional at a salon cause hair loss? It seems as though every question here about chemical relaxers involve doing it yourself or messing up and burning the scalp.

Professionals make mistakes on occasion so the use of relaxers always put you at risk for chemical burns. In the hands of experienced professionals, I would think that the risks are minimal.

With that said, I just met with a nice lady who had a professional use a relaxer on her hair about a year ago, and ended up with two thumb-print type bald spots that appeared after a 6 month course of treating open burn wounds on her scalp. I will be transplanting those thumb-print bare areas shortly.