User blog comment:IamJakuhoRaikoben/Chapter 450: Alone in all the World, Review./@comment-2214433-20150831081149/@comment-9595671-20150831155747

There's a condition called dwarfism which causes someone to grow to an unusual stature or size. I have a feeling that Makarov was born with this, so he wasn't able to become as tall as most people would.