A genetic condition that limits the growth of bones and may result in different medical complications1,2


A strong, flexible connective tissue that lines the joints and gives structure to the nose, ears, and other parts of the body. Cartilage is more widespread in the infant skeleton and is replaced by bone during growth1,3


The main type of cell that makes cartilage4


Fibroblast growth factor receptor 3

FGFR3 is a gene that provides instructions to make the FGFR3 protein. This protein regulates bone growth by limiting the formation of bone from cartilage, especially in the long bones5

Foramen magnum stenosis

A condition in which the opening at the base of the skull becomes narrowed, putting pressure on the brain or spinal cord2,6

Genu varum

A condition in which the knees curve out when standing with the feet and ankles together. This is also known as bowed legs7

Growth plate

A disc made of cartilage that sits at the end of a bone, where bone growth occurs. When children are fully grown, the cartilage in their growth plates hardens into bone8


Poor muscle tone. An infant with hypotonia may feel limp when held and have trouble holding up their head9


A condition in which an excessive curving of the spine results in an exaggerated rounding of the upper back1


A condition in which excessive curving of the spine results in an exaggerated arching of the lower back1


A condition where body weight is greater than what is considered healthy for height. This condition may lead to orthopedic complications like pain and reduced mobility in joints 2,10

Sleep apnea

A sleep disorder in which breathing stops and restarts many times during sleep11

Skeletal dysplasia

A condition that affects how cartilage and bone grow6

Spinal stenosis

A condition that occurs when the canal that contains the spinal cord is too narrow, which puts pressure on the spinal cord and nerves. Spinal stenosis can occur at different parts along the spine including cervical (neck) and lumbar (lower back)12,13


  1. Achondroplasia. MedlinePlus. Updated May 1, 2012. Accessed November 17, 2022.
  2. Savarirayan R et al. International Consensus Statement on the diagnosis, multidisciplinary management and lifelong care of individuals with achondroplasia. Nat Rev Endocrinol. 2022;18(3):173-189.
  3. Cartilage Disorders. MedlinePlus. Updated October 17, 2016. Accessed November 17, 2022.
  4. COMP gene. MedlinePlus. Updated February 1, 2008. Accessed November 17, 2022.
  5. FGFR3 gene. MedlinePlus. Updated February 1, 2020. Accessed November 17, 2022.
  6. Achondroplasia. Accessed November 17, 2022.
  7. Bowlegs. MedlinePlus. Updated October 10, 2020. Accessed November 17, 2022.
  8. Bones, Muscles, and Joints. Accessed November 17, 2022.
  9. Hypotonia. MedlinePlus. Updated November 1, 2021. Accessed November 17, 2022.
  10. Obesity. MedlinePlus. Updated November 29, 2016. Accessed December 20, 2022.
  11. Sleep Apnea. MedlinePlus. Updated March 30, 2021. Accessed November 17, 2022.
  12. Spinal Stenosis. MedlinePlus. Updated January 3, 2017. Accessed November 17, 2022. .
  13. Cervical Stenosis, Myelopathy and Radiculopathy. Accessed November 17, 2022. .