Sotos syndrome

Medical quality assurance by Dr. Albrecht Nonnenmacher, MD at August 19, 2016
StartDiseasesSotos syndrome

Sotos syndrome, which is also referred to as cerebral gigantism, is a very uncommon genetic disorder that affects growth. It is often accompanied by many intellectually disabilities and physical disabilities.

Contents

Definition & Facts

Sotos syndrome is characterized by abnormal bone growth, particularly in the skull, during the early years of childhood. Children with Sotos syndrome tend to have larger heads and taller heights than their peers, but their size becomes normalized as adults. This condition is a genetic disorder, so it can be inherited from family members or occur spontaneously.

Sotos syndrome is quite rare, and only 1 in 14,000 babies are born with this condition. Though it is impossible to reverse the genetic mutations that are the underlying cause of Sotos syndrome, it is possible to treat many of the symptoms of this condition. Sotos syndrome is very similar to a few other genetic disorders, including Weaver syndrome (also called Weaver-Smith syndrome) and Beckwith-Wiedemann syndrome, but it has a few distinct distances. 

Symptoms & Complaints

The symptoms of Sotos syndrome are often apparent at birth, and people with Sotos syndrome tend to have a rather high birth weight. As they develop into toddlers and young children, more issues related to Sotos syndrome may start to occur.

The abnormal bone growth of Sotos syndrome results in a distinctive appearance. Individuals with Sotos syndrome tend to have a very large head with a long face and a high forehead. This genetic disorder often causes downward-angled eyes and flushed or reddened cheeks.

Children with Sotos syndrome are both taller and heavier than other children who are their age. Though they grow quickly, they remain at a normal height once they become adults. People with Sotos syndrome may occasionally develop other physical issues, including seizures, improperly developing muscles, heart problems, defective kidneys, hearing loss, or vision loss, and scoliosis. They also have an increased risk of developing cancer.

In addition to health problems, many individuals with Sotos syndrome have behavioral problems or developmental delays. Though not all people with Sotos syndrome have these issues, they have a higher risk of being diagnosed with autism, intellectual disability, attention deficit hyperactivity disorder (ADHD), phobic disorders, anger management problems, and speech impairments.

Causes

Sotos syndrome is a genetic disorder, so it is caused by a mutated gene that does not contain the proper DNA sequence. Research has identified the NSD1 gene as having the primary genetic mutation that is responsible for Sotos syndrome, but other mutated genes can also be linked to the genetic disorder.

Chromosome 5 on the NSD1 gene is responsible for encoding proteins that regulate growth, but when it is mutated, growth is not properly monitored and halted. Though this genetic mutation explains the excessive growth during childhood, it is still unclear how the NSD1 mutation causes developmental disabilities and organ defects.

It is possible for an individual with Sotos syndrome to pass down the condition to their offspring, and since it is a dominant gene, only one parent needs to have the mutation. However, the condition is not always inherited, and almost 95 percent of all people with Sotos syndrome get it from spontaneous mutations. This happens when genes randomly mutate in a fetus while it is developing in utero. There are no known risk factors for a spontaneous NSD1 mutation, and Sotos syndrome occurs evenly among all genders, races, and ethnicities. 

Diagnosis & Tests

Though symptoms of Sotos syndrome are often evident at birth, it is not usually diagnosed right away. Typically, Sotos syndrome is only diagnosed after parents or doctors note that a child is suffering from developmental delays and abnormally fast growth. The distinct facial characteristics of Sotos syndrome - advanced bone growth and unusually large size of children with Sotos syndrome - are often enough to create a preliminary diagnosis.

However, the abnormal facial structure of people with Sotos syndrome and quick growth can also occur in individuals with other genetic abnormalities, so further testing is normally needed to confirm a diagnosis. Therefore, it is necessary to do genetic testing to determine the presence of any NSD1 mutations. In rare cases, patients may have Sotos syndrome without any NSD1 mutations, so extensive DNA sequencing is necessary to rule out other genetic disorders.

Treatment & Therapy

Treatment for Sotos syndrome will vary greatly depending on the individual symptoms that each patient is facing. Normally, a patient will need a coordinated treatment plan from various specialists, pediatricians, neurologists, geneticists, and therapists. People with Sotos syndrome will regularly receive checkups to ensure that their growth is not causing any other health problems.

If a toddler or infant is diagnosed with Sotos syndrome, they will need clinical evaluations with psychiatrists as they age. Early intervention can provide assistance for children with autism, ADHD, and behavioral problems, and this improves their chances of leading a more normal life. Many developmental and behavioral issues improve with time if a child receives treatment at an early age.

Common treatments for young children with Sotos syndrome include speech therapy, physical therapy, and special education. As they mature, patients with Sotos syndrome may need surgeries to correct spine issues, kidney defects, or eye and hearing issues. Though it is not possible to cure Sotos syndrome, regular medical examinations and prompt treatment of any issues help people with Sotos syndrome live long and happy lives.

Prevention & Prophylaxis

Because there are no known risk factors for spontaneous mutations that can cause Sotos syndrome, there is no way for parents to prevent their child from being born with this condition. However for cases in which mutations are not spontaneous, genetic counseling may be an option for parents to understand the risks that their child may have Sotos syndrome or other genetic disorders.

Since Sotos syndrome can cause so many other health issues, regular examinations to check the health of the eye, back, heart, and kidney are recommended to catch any concurrent health problems before they cause serious issues.