The terms "person of short stature," "little person," and "dwarf" are commonly used in the United States to refer to a person with a medical condition called "dwarfism." Although preferred terms vary by person and community, according to the Little People of America website, many people who experience dwarfism prefer the term "little person." According to Little People of America, dwarfism is "a medical or genetic condition that usually results in an adult height of 4 ft 10 inches (145 cm) or shorter, among both men and women." Unless physical stature is of relevance in a conversation, simply using a person's name is appropriate.
Additional information is available at the Little People of America website.