If you like these kinds of story, you will enjoy this story about PCSK9: https://www.nature.com/news/genetics-a-gene-of-rare-effect-1...
ANGPTL4: http://www.tum.de/en/about-tum/news/press-releases/short/art...
ASGR1: http://healthsciences.ku.dk/news/new-2016/mutation-protects-...
Growth hormone receptor: http://www.nbcnews.com/health/aging/little-people-ecuador-la...
And of course there are human loss of function myostatin mutants, but I can never find the articles I recall reading years back on some of the few known individuals.