AN 11-year-old boy with a rare form of dwarfism is one-in-a-million. Levi Krystosek, 11, has a rare form of dwarfism called Jansen Metaphysical Chondrodysplasia, which affects the growth of bones and causes considerable pain, meaning he is only 38 inches tall. There are approximately only 30 known cases of JMC in the world, and five genetically confirmed cases in the US.