Larsen Syndrome

What is Larsen syndrome?

Larsen syndrome is a very rare genetic disorder that impacts the development of many of the bones in the body. The syndrome was first described by Loren J. Larsen, MD, in a journal article in 1950, and it was subsequently named after him.

The syndrome, which affects about 1 in 100,000 babies each year, can cause many different symptoms, even in children in the same family who have the disorder.

People with Larsen syndrome have normal intelligence.


Larsen syndrome is an autosomal dominant genetic disorder, caused by a mutation in a gene that is important to normal skeletal development before birth, called FLNB (filamin B). 

An autosomal dominant genetic disorder means a child can inherit the condition from either parent who has the abnormal gene — whether the parent has the disease or not. In autosomal recessive genetic disorders, both parents must have the abnormal gene in order to pass the condition onto their child.

Signs and symptoms

While bones and joints can show symptoms of Larsen syndrome, facial features can also be affected. Children with Larsen syndrome may have:

  • Spinal deformity such as scoliosis or kyphosis and cervical spine abnormalities
  • Foot disorders such as club foot
  • Dislocated hips, knees and elbows
  • Short stature
  • Abnormally loose joints
  • Extra bones in the wrists and ankles
  • Flat, square-shaped tips of fingers
  • Craniofacial anomalies such as a prominent forehead, flattened bridge of the nose, wide-set eyes and cleft palate
  • Hearing loss because some bones in the ears did not form properly
  • Respiratory problems

Testing and diagnosis

Diagnostic evaluation for Larsen syndrome begins with a thorough medical history and physical examination of your child.

At Children’s Hospital of Philadelphia (CHOP), clinical experts use a variety of diagnostic tests to diagnose Larsen syndrome and possible complications, including:

  • X-rays, which produce images of bones.
  • Magnetic resonance imaging (MRI), which uses a combination of large magnets, radiofrequencies and a computer to produce detailed images of organs and structures within the body.
  • Computed tomography (CT) scan, which uses a combination of X-rays and computer technology to produce cross-sectional images ("slices") of the body.
  • EOS imaging, an imaging technology that creates 3-dimensional models from two planar images. Unlike a CT scan, EOS images are taken while the child is in an upright or standing position, enabling improved diagnosis due to weight-bearing positioning.
  • Blood tests, which can help determine drug usage and effectiveness, biochemical diseases and organ function.


Because Larsen syndrome affects several body systems, treatment for the condition varies. In some cases, careful monitoring may be all that is required. In other cases, surgery may be needed to address specific aspects of the condition.

At Children’s Hospital of Philadelphia, we practice collaborative, family-centered care. A team of expert clinicians — including leading orthopaedic surgeons and physicians, pediatric nurses, physical and occupational therapists, psychologists and other specialists — will partner with you in the care of your child.

Many of the complications of Larsen syndrome are evident at birth and can be treated while your child is young. Two examples of this are club feet and craniofacial anomalies. At Children’s Hospital, orthopaedic surgeons in our Leg and Foot Disorders Program, and plastic surgeons in our Neonatal Craniofacial Program and Craniofacial Program will work with your family to create an individualized care plan for your child.

Other complications of Larsen syndrome may only become evident — or problematic — as your child grows. This is often true for spinal deformities, such as scoliosis, cervical spine disorders and joint disorders.

Depending on your child’s needs, orthopaedic specialists from our Spine Program or our Neuromuscular Program will treat your child.

Every child’s condition is different, so treatment is determined on a case-by-case basis. For example, if your child has scoliosis, our team of specialists will consider the severity of the curve, where it occurs in the spine, and your child's age and stage of growth, before determining the best course of action.

Treatment may include non-surgical options such as bracing and physical therapy, or surgical options such as spinal fusion or implanting growing rods to stabilize your child’s spine as she continues to grow.

Follow-up care

Your child with Larsen syndrome should continue to be monitored by an orthopaedic physician into adulthood.

If your child needed spine surgery, he or she will need to see the orthopaedic surgeon about one to two weeks after surgery, then again at three and six months post-surgery. After that, annual monitoring by trained clinicians is strongly encouraged to ensure any problems are spotted and treated as soon as possible.

Additionally, physicians may recommend your child see several different specialists because so many body systems are involved in a diagnosis of Larsen syndrome.

For example, your child may see:

  • An orthopaedist for any spine, cervical spine, bone- and muscle-related issues
  • An otolaryngologist for regular hearing evaluations
  • A plastic surgeon for cleft palate
  • A neurologist for any nerve issues
  • A pulmonologist for any breathing issues
  • Physical therapists and occupational therapists to expand your child’s physical dexterity and skill

During follow-up visits, X-rays and other diagnostic testing may be done. The goal of continued monitoring is to help spot any irregularities in growth or development and to address health issues as they develop.

Follow-up care and ongoing support and services are available at our Main Campus and throughout our CHOP Care Network. Our team is committed to partnering with parents and referring physicians to provide the most current, comprehensive and specialized care possible for your child.


Children with Larsen syndrome live into adulthood and can lead normal lives with careful medical care.

In some cases, individuals with Larsen syndrome may experience painful or dislocated joints. These individuals may need a hip or knee replacement in early adulthood.

Next Steps
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