Which is the most common type of dwarfism?

Dwarfism means that a person has short stature due to a genetic or medical condition, with an adult height of 4 feet, 10 inches or less. There are an estimated 300 types of dwarfism.

Achondroplasia, the most common type of dwarfism makes up 75 percent of all cases of dwarfism. Physical traits of this type of dwarfism include an average size upper body, but the arms, legs and fingers are noticeably shorter, the head is usually larger with a more prominent forehead than average height and adults can develop an arch in the lower back or bowed legs. The average height for an achondroplasiac is around 4 feet.

The majority of people with dwarfism experience gene mutations that interfere with the normal development of the cartilage and bones in the body. Since arms and legs have the longest bones, any interference in normal bone development usually results in shorter limbs leading to short stature. With achondroplasia, there is a problem with the gene that tells the body to convert cartilage to bone while growing, especially in the long bones.

Most cases of achondroplasia can be diagnosed before birth through the use of ultrasound in the later stages of pregnancy. Ultrasounds can show shorter-than-average arms and legs, as well as whether the baby's head is larger than average.

The terms usually preferred by people with this condition are short-statured or little person rather than dwarf.