What is Sotos Syndrome?

Sotos syndrome is a rare genetic condition characterized by excessive physical growth in infancy that continues until age three or four. People with Sotos syndrome usually have developmental delays and may require extra support from therapists, counselors, and medical personnel throughout their lifetime, but the condition is not fatal and is not always passed on to future generations.

First Descriptions of Sotos Syndrome

Juan F. Sotos and his colleagues first described what is now called Sotos syndrome in the New England Journal of Medicine in 1964. The study investigated a group of children exhibiting the clinical features now recognized as hallmarks of the disease. At that time, it was referred to as cerebral gigantism, as most children with the syndrome presented with distinctive long, narrow facial features and a large head circumference. It is estimated that Sotos syndrome affects one out of every 10,000 to 14,000 fetuses.

Cause: Gene Mutation

In 2002, Japanese scientists discovered that a mutation in the NSD1 gene is responsible for Sotos syndrome. In about 95 percent of cases, the mutation is spontaneous and not inherited. Interestingly, the effects of the mutation differ between people with Sotos syndrome in the United States and Europe and those in Japan. In the former regions, the mutation is caused by small deletions while in Japan, the most common genetic change is a larger deletion of genetic material from a single region.

An Autosomal Dominant Condition.

Most cases of Sotos syndrome occur due to spontaneous mutation, but it is still important to understand how the gene is passed down genetically. A person with Sotos syndrome has a 50 percent chance of passing it on to his or her child. Autosomal dominant conditions occur when one parent has a normal gene and a mutated gene on a single pair of chromosomes. If the offspring gets one copy of the mutation, they will have Sotos syndrome. In contrast, an autosomal recessive trait requires both parents to have the mutation and for the offspring to receive a copy from each parent.

Physical Characteristics of Sotos Syndrome

In infancy, babies with Sotos syndrome have round faces with a large, elongated forehead. As they get older, the forehead gets longer and a pointed chin becomes prominent. Other physical features include:

• Receding hairline
• Flattened nose bridge
• Wide spacing between eyes with outside edges slanting downward
• Forward-slanting nostrils
• High, arched palate
• Large ears

Children with Sotos Syndrome grow much faster than their unaffected siblings and peers. They may also have large hands and feet, scoliosis, weak muscle tone, and an awkward gait.

Developmental Characteristics of Sotos Syndrome

Infants and toddlers with Sotos syndrome usually developmental delays for milestones like rolling, sitting, crawling, and walking. Children may demonstrate poor coordination and have trouble with both gross and fine motor skills. Language skills are often delayed as well. Some children with Sotos syndrome do not speak until they are two or three years old. Intellectual and developmental problems can arise, too, including ADHD, OCD, impulse control problems, and aggression. Some children with Sotos syndrome have autism, while others have only mild to moderate learning disabilities.

Diagnosis

Doctors typically make a diagnosis of Sotos syndrome when a child is in infancy or a toddler. Some skilled and experienced pediatricians may pick up on craniofacial abnormalities during infant well-visits, but it may take symptoms years to become pronounced enough to arouse suspicion. Early signs include excessive growth and difficulty meeting developmental milestones. Initial testing involves a thorough medical history and physical exam. CT scans, MRIs, and x-rays can rule out other conditions. If the doctor suspects Sotos syndrome, he or she may do genetic testing.

Treatment

There is no cure for Sotos syndrome. Treatment focuses on managing symptoms and improving quality of life. Some interventions may include:

• Occupational therapy
• Speech therapy
• Behavioral therapy
• Medication to manage ADHD
• Counseling

Other symptoms are managed as they arise, such as glasses to correct vision problems or hearing aids to manage auditory issues. People with Sotos syndrome are at a higher risk than the general population of developing cancer or other tumors, so regular screening is recommended. Doctors may also recommend regular heart and kidney tests.

Sotos Syndrome in Childhood

If diagnosed during infancy, early intervention can give children with Sotos syndrome superior support and nurturing. Infant stimulation, as well as speech, occupational, and physical therapy are all very beneficial. When they reach school age, some children with Sotos syndrome may be able to participate in regular classrooms with appropriate support. During school years, some children develop behavior problems and may require more one-on-one attention and assistance.

Sotos Syndrome in Adulthood

Although children with Sotos syndrome are large for their age, by the time they reach adulthood, they are usually in the normal range for height and weight. Some overcome developmental difficulties and have normal intellect. Adults with Sotos syndrome are fully capable of living ordinary lives. There’s no reason they cannot have children, though there is a 50 percent chance their children will have Sotos syndrome. Genetic testing can be done early so the child gets the interventions he may need to support development. People with second-generation Sotos syndrome have no chance of genetically passing on the disease.

Living with Sotos Syndrome

People with Sotos syndrome can have normal lives as long as they get the support they need along the way. Physical and occupational therapy can help with motor skills, and speech therapy can be effective at working through speech delays in early years. Adults may be restricted from certain activities such as driving, but many are employed and can live independently.