Meyahealth
HomeGeneticsConditionLarsen syndrome
Back to Condition
Larsen syndrome
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Condition

Larsen syndrome

Larsen syndrome is a genetic disorder affecting skeletal development, characterized by joint dislocations, distinct facial features, and potential respiratory or spinal complications.

Overview

Larsen syndrome affects bone development throughout the body. Signs and symptoms vary widely, even within the same family. Common features include:

  • Joint dislocations: Affected individuals are usually born with dislocations of the hips, knees, or elbows.
  • Foot deformities: Inward- and upward-turning feet (clubfoot) are common.
  • Skeletal abnormalities: Small extra bones in the wrists and ankles; blunt, square-shaped (spatulate) fingertips; and short stature.
  • Facial features: Prominent forehead (frontal bossing), flattened nasal bridge, midface hypoplasia, and wide-set eyes.
  • Other symptoms: Cleft palate, hearing loss, joint hypermobility or restricted movement, and spinal abnormalities (kyphosis or scoliosis).

Some individuals may experience respiratory problems due to airway issues or spinal cord compression. Intellectual function is usually unaffected, and individuals can survive into adulthood.

Frequency

Larsen syndrome occurs in approximately 1 in 100,000 newborns, though it may be underdiagnosed due to its similarity to other conditions.

Causes

Mutations in the FLNB gene cause Larsen syndrome. This gene provides instructions for making the protein filamin B, which is essential for building the network of filaments that gives structure to cells (the cytoskeleton). Filamin B is particularly important for the development of cartilage and its conversion to bone (ossification). Mutations result in an abnormal protein that interferes with the growth and maturation of cartilage-forming cells, leading to the skeletal signs of the syndrome.

Inheritance

Larsen syndrome is typically inherited in an autosomal dominant pattern, where one copy of the altered gene is sufficient to cause the disorder. While most cases are inherited or result from new mutations, rare instances of autosomal recessive inheritance have been reported, sometimes linked to germline mosaicism in a parent.

Frequently Asked Questions

Because of craniofacial abnormalities and potential spinal cord compression, infants may develop airway obstruction or restrictive lung disease. Parents should watch for rapid breathing, wheezing, cyanosis, or difficulty feeding. If any of these signs appear, seek emergency care promptly, as airway compromise can become life‑threatening.
Confirmation is done via targeted sequencing of the FLNB gene from a blood sample. Families should receive counseling about the autosomal dominant inheritance, the possibility of de‑novo mutations, and the implications for future pregnancies, including options for prenatal testing or pre‑implantation genetic diagnosis.===
Newborns with Larsen syndrome frequently present with dislocations of the hips, knees, or elbows. The first step is gentle reduction by a pediatric orthopedic specialist, often performed in the delivery room or shortly after birth. Once reduced, the joint is usually immobilized with a splint or cast for several weeks, and the infant is closely monitored for re‑dislocation. Early referral to a pediatric orthopedic team is essential to plan for potential future surgeries and to prevent chronic joint instability.
dults with spinal curvature often benefit from a combination of physical therapy, bracing, and, in severe cases, surgical correction such as spinal fusion. The choice depends on the curvature magnitude, progression rate, and symptom severity. Regular imaging every 6–12 months helps guide timing of intervention.
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.

Meyahealth

Ⓒ 2026. All rights reserved by MEYA

About UsTerms & PolicyFAQ