Achondroplasia is a bone growth disorder that causes disproportionate dwarfism. Dwarfism is defined as a condition of short stature as an adult. People with achondroplasia are short in stature with a normal sized torso and short limbs. It’s the most common type of disproportionate dwarfism. The disorder occurs in approximately 1 in 25,000 live births, according to Columbia University Medical Center (CUMC). It’s equally common in males and females. During early fetal development, much of your skeleton is made up of cartilage. Normally, most cartilage eventually converts to bone. However, if you have achondroplasia, a lot of the cartilage doesn’t convert to bone. This is caused by mutations in the FGFR3 gene. The FGFR3 gene instructs your body to make a protein necessary for bone growth and maintenance. Mutations in the FGFR3 gene cause the protein to be overactive. This interferes with normal skeletal development.

In more than 80 percent of cases, achondroplasia isn’t inherited, according to the National Human Genome Research Institute (NHGRI). These cases are caused by spontaneous mutations in the FGFR3 gene. About 20 percent of cases are inherited. The mutation follows an autosomal dominant inheritance pattern. This means that only one parent needs to pass down a defective FGFR3 gene for a child to have achondroplasia. nfants born with homozygous achondroplasia are usually stillborn or die within a few months of being born. If there’s a history of achondroplasia in your family, you may want to consider genetic testing prior to becoming pregnant so that you fully understand your future child’s health risks.