Eddie Luther, age 14, of Bowling Green, Ohio, for his question:
WHAT CAUSES A PERSON TO BECOME A DWARF?
A dwarf is an unusually small adult human being. Dwarfs grow no more than 4 1/2 feet tall. Human dwarfism generally occurs as the result of an underdeveloped skeleton.
The growth of the skeleton depends on the formation of tissue called cartilage. Dwarfism results when the cartilage cells do not grow and divide properly. Such improper development may occur because of defective cartilage cells or interference with the growth of otherwise normal cartilage cells.
Interference with the growth of normal cartilage cells results in hormonal dwarfism or nonhormonal dwarfism, depending on what causes the interference.
Chondrodystrophic (CQ) dwarfism occurs when only certain cartilage cells are defective. The term chondrodystrophic means underdeveloped cartilage. Most chondrodystrophic dwarfs have abnormal body proportions. The defective cells occur only in the spine or only in the arms and legs. Consequently, either the torso (chest, abdomen and hips) or the limbs grow unusually short.
Chromosome related dwarfism results when all the cells of the body, including the cartilage cells, are defective. Such defects involve a disturbance in the number of chromosomes per cell. The chromosomes are the cell structures that contain genes.
Hormonal dwarfism may occur when a hormone deficiency interferes with the growth of normal cartilage cells. Hormones are chemical substances that are secreted by various glands. They circulate through the blood and influence the cells of the body to act in certain ways. An insufficient amount of a growth producing hormone leads to a stunted growth.
Nonhormonal dwarfism occurs if disease or improper nourishment blocks the growth of cartilage cells.
Children who lack a certain growth promoting hormone may be treated by a doctor. Since the mid 1960s, physicians have given growth hormone (GH) from the pituitary gland to children who lack this hormone. But only limited amounts of GH are available and many young remain untreated.
Insulin and thyroxin, which are readily available, may be given to stimulate growth in children affected by diabetes or cretinism.
Nonhormonal dwarfism can occur as a result of disease or improper nourishment. For example, a disease of the bowel or kidneys may interfere with growth. Many nonhormonal interferences can be corrected, with rapid "catch up" growth taking place after treatment.
Dwarfism occurs both in individual organisms and in entire groups of organisms. Such groups include African pygmies, Shetland ponies and various kinds of dwarf trees. In general, dwarfism occurs as a result of defective cells, disease or poor nutrition.