There are many diseases that alter a child's appearance, including Down syndrome, Cri-du-chat syndrome or Lejeune's syndrome, and Williams syndrome.

But I think you're referring to one of the many genetic disorders that can cause short stature and asymmetrical limb growth, some of which include dwarfism, Russell Silver Syndrome, chondrodystrophy, and many more. Each of these diseases causes specific changes in the growth and appearance of a child, and all often come with a myriad of health and developmental problems.