CHD2-related syndrome happens when there are changes to the CHD2 gene. These changes can keep the gene from working as it should.

Each family is different. A geneticist or genetic counselor can give you advice on the chance that this will happen again in your family.

The risk of having another child who has CHD2-related syndrome depends on the genes of both birth parents.

• If neither birth parent has the same gene change found in their child, the chance of having another child who has the syndrome is on average 1 percent. This 1 percent chance is higher than the chance of the general population. The increase in risk is due to the very unlikely chance that more of the mother’s egg cells or the father’s sperm cells carry the same change in the gene.
• If one birth parent has the same gene change found in their child, the chance of having another child who has the syndrome is 50 percent.

For a symptom-free sibling, a brother or sister, of someone who has CHD2-related syndrome, the risk of having a child who has the syndrome depends on the symptom-free sibling’s genes and their parents’ genes.

• If neither parent has the same gene change found in their child who has the syndrome, the symptom-free sibling has a nearly 0 percent chance of having a child who has CHD2-related syndrome.
• If one birth parent has the same gene change found in their child who has the syndrome, the symptom-free sibling has a small chance of also having the same gene change. If the symptom- free sibling has the same gene change as their sibling who has the syndrome, the symptom-free sibling’s chance of having a child who has CHD2-related syndrome is 50 percent.

For a person who has CHD2-related syndrome, the risk of having a child who has the syndrome is about 50 percent.

As of 2024, at least 307 people with CHD2-related syndrome have been identified in a medical clinic. The first case of CHD2-related syndrome was described in 2012.

People with CHD2-related syndrome may look different. Appearance can vary and can include, but is not limited to, smaller than average head size and height.

Scientists and doctors have only just begun to study CHD2-related syndrome. At this point, there are no medicines designed to treat the syndrome. A genetic diagnosis can help people decide on the best way to track the condition and manage therapies. Doctors can refer people to specialists for:

• Physical exams and brain studies. An EEG, or electroencephalogram, which measures the brain’s electrical activity, or an MRI scan, a procedure that shows the structure of the brain, can help diagnose epilepsy and guide treatment.
• Genetics consults
• Development and behavior studies
• Other issues, as needed

A developmental pediatrician, neurologist, or psychologist can follow progress over time and can help:

• Suggest the right therapies. This can include physical, occupational, speech, or behavioral therapy.
• Guide individualized education plans (IEPs).

Specialists advise that therapies for CHD2-related syndrome should begin as early as possible, ideally before a child begins school.

If seizures happen, consult a neurologist. There are many types of seizures, and not all types are easy to spot. To learn more, you can refer to resources such as the Epilepsy Foundation’s website: epilepsy.com/learn/types-seizures.

Learning

Almost everyone with CHD2-related syndrome has intellectual disability, ranging from mild to severe. People who have the syndrome generally need special educational support.

• 91 out of 102 people have mild to severe intellectual disability (89 percent).

Behavior

Brain

People who have CHD2-related syndrome might have seizures. Sometimes seizures are caused by fevers or flashing lights. Seizures might not be controlled by medicines. Age of seizure onset can range from 6 months to over 12 years old. Average age of seizure onset is 2 and a half years. In the medical research, there has not been one anti-seizure medication shown to be beneficial to people with CHD2-related syndrome.

More than one-half have seizures that are caused by flashing lights.

• 108 out of 113 have seizures (96 percent).
• 50 out of 88 have seizures caused by flashing lights (57 percent).

Development

More than one-half have developmental delays before seizure onset. More than one-third are shorter than average, and some have scoliosis.

• 61 out of 83 have developmental delays before seizure onset (73 percent).
• 12 out of 34 are shorter than average (35 percent).
• 5 out of 68 have scoliosis (7 percent).

Coalition to Cure CHD2 (CCC)

Coalition to Cure CHD2 (CCC) is a 100% volunteer-run organization fueled by their desire to help children & others with CHD2-related disorders. Their mission is to improve the lives of those affected by CHD2-related disorders by funding research necessary for uncovering a cure. Their vision is to find safe and effective treatments that will cure CHD2-related disorders.

• CureCHD2.org
• www.facebook.com/groups/chd2support

Simons Searchlight

Simons Searchlight is an online international research program, building an ever growing natural history database, biorepository, and resource network of over 175 rare genetic neurodevelopmental disorders. By joining their community and sharing your experiences, you contribute to a growing database used by scientists worldwide to advance the understanding of your genetic condition. Through online surveys and optional blood sample collection, they gather valuable information to improve lives and drive scientific progress. Families like yours are the key to making meaningful progress. To register for Simons Searchlight, go to the Simons Searchlight website at www.simonssearchlight.org and click “Join Us.”

• Learn more about Simons Searchlight: www.simonssearchlight.org/frequently-asked-questions
• Simons Searchlight CHD2 webpage: www.simonssearchlight.org/research/what-we-study/chd2
• Simons Searchlight Facebook group for CHD2 families: www.facebook.com/groups/searchlight.chd2

Other community resources:

• CHD2 Research and Support Group: www.facebook.com/groups/1462485137354985