An Overview of Sotos Syndrome

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Sotos syndrome is a rare genetic condition that causes excessive physical growth during the first two decades of life, starting from infancy and going into the teen years. Sotos is sometimes accompanied by autism, speech impairments, and intellectual, social, and motor delays. While the condition does affect children in the school years and may continue to cause problems into adulthood, it is non-life threatening and most people with Sotos have normal life expectancies.   

According to the Genetics Home Reference page of the National Institutes of Health, Sotos syndrome is believed to occur in one out of every 10,000 to 14,000 births. Researchers speculate the true incidence may be closer to one in every 5,000 births, as other conditions cause similar symptoms and misdiagnoses are possible.

Symptoms

Sotos syndrome is characterized by overgrowth, especially in the bones. Affected persons have facial abnormalities that are especially significant in childhood. This includes having a head that is longer and wider than normal and a pointed chin.

Affected infants and children with Sotos grow quicker than other children their age. They will be taller than their siblings and peers.  

Additional physical characteristics and symptoms may include: 

  • Large hands and feet
  • High forehead
  • Weak muscle tone
  • Flushed cheeks
  • Down-slanting eyes and a large distance between the eyes
  • Awkward gait (walk)
  • Scoliosis, a sideways curve of the spin
  • Seizures, which result from abnormal brain activity
  • Hearing loss
  • Vision problems
  • Kidney and heart problems

Individuals may have intellectual impairment and behavioral problems, including: 

Developmental and intellectual problems in children may include: 

  • Speech and language problems, including stuttering 
  • Learning disabilities
  • Clumsiness
  • Motor skill problems 

Sotos in Adulthood

Adult height and weight will stabilize and be somewhat normal, although there is one case of a 21-year-old man with Sotos who is currently 7 feet, 8 inches tall and weighs around 500 pounds. Many adults with this condition will have normal intellect. However, any childhood intellectual disability will remain. Adults with Sotos will continue to have coordination and motor skill issues.

Causes

Sotos syndrome is a genetic disorder caused by a mutated NSD1 gene. According to the Genetic and Rare Diseases Information Center (GARD), 95 percent of Sotos cases are not inherited. However, the chance of a parent with Sotos passing the condition on is 50 percent.

There are no other known risk factors or causes of Sotos syndrome. Further, researchers don’t know what causes the genetic mutation or how to prevent it.

Diagnosis

A Sotos syndrome diagnosis is made early in life, either in infancy or in the first few years of life. Newborn testing does not include testing for Sotos, but doctors will test for it when symptoms are noticed. It may take months or years for testing to occur and for symptoms to be pronounced.

Testing for Sotos starts with a physical exam and medical history, including symptoms. X-rays, CT scans, and MRIs can help with diagnosis and in ruling out other problems. Genetic testing may also be done to check for mutations in the NSD1 gene.

Many children with Sotos may also receive a diagnosis of autism. Autism is a developmental disorder affecting communication and behavior. It is generally managed with a variety of therapies, including behavioral and speech therapies, as needed.

Treatment

There is no cure for Sotos syndrome. Further, there is no specific one treatment for Sotos. Treatment usually involves managing symptoms and correcting problems that can be corrected. 

Treatment may include: 

  • Speech therapy
  • Occupational therapy
  • Behavioral therapy
  • Medications to manage attention-deficit hyperactivity disorder (ADHD), a brain disorder marked by inattention and hyperactivity-impulsivity. These behaviors interfere with functioning and development, especially in childhood.
  • Counseling
  • Hearing aids to correct hearing loss
  • Glasses to manage vision problems

Other medical conditions will also be treated, as needed. 

It is important for people with Sotos to have regular heart and kidney testing. Further, cancer and tumor risks are higher for people with Sotos syndrome, so regular screening is a good idea. However, Sotos itself is non-life threatening and most people with Sotos have normal life expectancies.

A Word From Verywell

Sotos syndrome is a genetic disorder caused by a mutation of the NSD1 gene. The two main symptoms of Sotos syndrome are overgrowth and intellectual disability. It is often diagnosed in infancy or early childhood. Once growth stops, adults with Sotos can maintain normal height and weight, and even intellect. Further, many adults with Sotos can lead long and fulfilling lives.

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