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Kniest dysplasia
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Condition

Kniest dysplasia

Kniest dysplasia is a skeletal disorder characterized by short stature, joint disease, and vision and hearing impairments.

Overview

Kniest dysplasia is a skeletal disorder where individuals are born with a short torso and short arms and legs. Adult height typically ranges from 42 to 57 inches. A distinguishing feature is abnormal cartilage; when viewed with medical imaging, the cartilage contains tiny holes, making it appear like Swiss cheese. This abnormal cartilage interferes with normal bone development.

Symptoms

  • Skeletal abnormalities: Rounded upper back that curves to the side (scoliosis), flattened bones of the spine (platyspondyly), dumbbell-shaped leg bones, and inward- and upward-turning feet.
  • Facial features: Distinctive features include a round, flat face with prominent eyes. Some infants are born with an opening in the roof of the mouth (cleft palate).
  • Joints: Enlarged joints that cause pain, restrict movement, and lead to early-onset arthritis.
  • Sensory issues: Hearing loss and vision problems, such as severe nearsightedness and tearing of the light-sensitive tissue at the back of the eye (retinal detachment).
  • Respiratory: Infants may have breathing problems due to a windpipe that is too flexible.

Causes

Kniest dysplasia is caused by variants in the COL2A1 gene. This gene provides instructions for making type II collagen, which is essential for the normal growth and development of bones and other connective tissues. Variants in this gene lead to the production of an abnormal version of the protein, which disrupts the formation of stable, functional type II collagen molecules.

Inheritance

This condition is inherited in an autosomal dominant pattern, meaning one copy of the altered gene in each cell is sufficient to cause the disorder. The majority of cases result from a new (de novo) variant that occurs during the formation of reproductive cells or early embryonic development. In some cases, a parent may carry the variant in a small number of their cells, known as somatic mosaicism.

Frequently Asked Questions

Kniest dysplasia can be suspected during pregnancy if a fetus shows short limbs or a curved spine on ultrasound. After birth, a pediatrician may order a skeletal survey (X‑rays of the spine, pelvis, and limbs) and a genetic test for COL2A1 mutations. Early genetic confirmation allows for prompt monitoring of growth, joint health, and sensory issues.
Kniest dysplasia follows an autosomal dominant pattern, giving a 50 % chance of passing the mutation to each child. Genetic counseling can discuss prenatal testing (chorionic villus sampling or amniocentesis) and pre‑implantation genetic diagnosis (PGD) with IVF to select embryos without the COL2A1 variant. Parents can also consider adoption or using a donor egg or sperm if they wish to avoid the risk.
Because hearing loss and vision problems are common, an audiology evaluation should be done by 6 months of age and repeated annually. Ophthalmology visits should begin by 12 months to screen for myopia, retinal detachment, or other ocular abnormalities, and should continue at least every 1–2 years.
Regular physical therapy focused on gentle range‑of‑motion and strengthening exercises helps maintain joint mobility. Orthotic devices or braces can support weak joints, and low‑dose NSAIDs or topical analgesics may reduce pain. In some cases, joint‑preserving surgeries or arthroscopic procedures are considered when arthritis progresses.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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