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What is Kleefstra syndrome?

Kleefstra syndrome is a rare genetic condition that affects development and involves many body systems. People with Kleefstra syndrome usually have distinct facial features, developmental delay, intellectual disability, low muscle tone (hypotonia), and communication difficulties. Kleefstra syndrome is caused by a mutation in a gene called EHMT1 or the deletion of a specific region of chromosome 9 that includes EHMT1.

Other names for Kleefstra syndrome include 9q-syndrome, 9q34.3 deletion syndrome, and chromosome 9q deletion syndrome.

Kleefstra syndrome: Cracking the code

Diagnosed with Kleefstra syndrome, Paul is in a study that's helping to define it, while scientists study its effects on sleep.

Kleefstra Syndrome | Symptoms & Causes

What are the symptoms of Kleefstra syndrome?

Kleefstra syndrome causes a range of symptoms that can differ from person to person. Symptoms may include:

In some cases, symptoms may include severe respiratory infections. Children with Kleefstra syndrome may have trouble communicating or interacting socially. Some adolescents may lose interest (apathy), lose developmental skills (regression), or become unresponsive (catatonic).

What causes Kleefstra syndrome?

Kleefstra syndrome is a genetic condition that is caused by the loss of function of one copy of the EHMT1 gene. In about 50 percent of cases, a variation or “mutation” in one copy of the EHMT1 causes the loss of function. The remaining cases are caused by the deletion of one copy of a segment of chromosome 9, which includes the gene EHMT1.

The role of EHMT1 is to produce an enzyme, histone methyltransferase 1, that controls the activity of other genes in the body. When one copy of EHMT1 loses its function, it affects a large number of other genes involved in development and functioning of organs and tissues throughout the body.

Kleefstra syndrome is rarely passed from a parent to their child. It usually happens sporadically, with no family history of the disease. This happens because the genetic changes are de novo, which means new mutations or deletions. Individuals with Kleefstra syndrome have one standard copy of EHMT1 and one that does not work or is deleted. This means they have a 50 percent chance of passing the condition on with each pregnancy.

Kleefstra Syndrome | Diagnosis & Treatments

How is Kleefstra syndrome diagnosed?

The diagnosis of Kleefstra syndrome depends on the identification of a mutation or deletion involving the gene EHMT1. Your doctor will determine whether genetic testing is appropriate after reviewing your child’s medical history and examining their nervous system.

After being diagnosed with Kleefstra syndrome, your child may also need magnetic resonance imaging (MRI) to create two- and three-dimensional images of their brain and spinal cord. Your child may also need to be evaluated for epilepsy, heart or kidney defects, or sleep disorders.

How is Kleefstra syndrome treated?

Your child’s doctor may recommend referral to an early intervention program if your child is under 4 years of age and has developmental delay or intellectual disability. They may also recommend ongoing management of these issues as your child gets older.

Your child’s doctor may recommend treatments for gastrointestinal issues. Gastroesophageal reflux (GERD) occurs when stomach acid flows back into the esophagus. Treatment for GERD varies by age but can include medication to reduce stomach acid or to make the stomach empty faster.

Your doctor may prescribe medications to treat seizures or sleep problems. Hearing loss may be treated with hearing aids or cochlear implants. Your doctor may also recommend orthopedic treatments later in life.

Your child may also need physical therapy, speech therapy, and occupational therapy to improve development and long-term prognosis. Your doctor may also suggest alternative methods of communication, such as sign language, if your child’s verbal skills are lacking. Behavioral therapy may be recommended to determine your child’s behavioral and social skills and improve outcomes.

How we care for Kleefstra syndrome

The Kleefstra Syndrome Clinic and Neurogenetics Program at Boston Children’s Hospital are dedicated to the comprehensive care of children and adolescents with Kleefstra syndrome and many other genetic disorders. Our team of nationally recognized experts are also leaders in basic and clinical research and partner with leading organizations to provide the best possible treatments to our patients.

Kleefstra Syndrome | Programs & Services