By Davide Caramellino
People with achondroplasia have short stature, with an average adult height of 131 centimeters (4 feet 4 inches) for males and 123 centimeters (4 feet 0 inches) for females. Achondroplastic adults are known to be as short as 62.8 cm (2 ft 0.7 in). The disorder itself is caused by a change in the gene for fibroblast growth factor receptor 3 (FGFR3), which causes an abnormality of cartilage formation. If both parents of a child have achondroplasia, and both parents pass on the mutant gene, then it is very unlikely that the homozygous child will live past a few months of its life. The prevalence is approximately 1 in 28,000,000.
Dwarfism can be diagnosed before birth by the use of prenatal ultrasound. A DNA test can be performed before birth to detect homozygosity, where two copies of the mutant gene are inherited, a lethal condition leading to stillbirths. But homozygosity is the only dangerous form of dwarfism, if only one gene is received it is not lethal.