Dwarfism (UK: ; US: ) occurs when an individual person or animal is short in stature resulting from a medical condition caused by slow growth. In humans, dwarfism is sometimes defined as an adult height of less than . Dwarfism can be caused by more than 300 distinct medical conditions, such that the symptoms and characteristics of individuals with dwarfism vary greatly. Disproportionate dwarfism is characterized by one or more body parts being relatively large or small in comparison to those of an average-sized adult, with growth variations in specific areas being apparent. In cases of proportionate dwarfism, the body appears normally proportioned, but is unusually small.