SCN2A-related syndrome happens when there are changes to the SCN2A 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 SCN2A-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 SCN2A-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 SCN2A- 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 SCN2A-related syndrome is 50 percent.

For a person who has SCN2A-related syndrome, the risk of having a child who has the syndrome is about 50 percent.

As of 2019, about 200 people in the world with changes in the SCN2A gene have been described in medical research.

The first case of SCN2A-related syndrome was described in 2002. Scientists expect to find more people who have the syndrome as access to genetic testing improves.

People who have SCN2A-related syndrome generally don’t look different.

Epilepsy is common in people who have SCN2A-related syndrome. In some cases, seizures that are linked to SCN2A-related conditions cannot be controlled. But, for infants whose seizures begin before 3 months of age, a class of medication known as sodium channel blockers, such as phenytoin and carbamazepine, may be helpful (Wolff et al., 2017). Note that this is the opposite of best practice guidelines for neonatal seizures.

Children who have autism and developmental delay whose seizures begin after 12 months of age respond best to a different set of medications, including levetiracetam, benzodiazepines, and valproate.

Little information is available on how to best treat infants whose seizures begin between 3 and 12 months of age. Some studies suggest that sodium channel blockers are the best option. Other studies have found improvement with medications including lidocaine (Foster et al., 2017; Ogiwara et al., 2009), ethosuximide (Wolff et al., 2017), and acetazolamide (Leach et al., 2016; Liao et al., 2010). There is not enough data on these medications to give specific advice.

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.

It is important to seek care and therapies to help the person’s brain and nervous system develop and operate as well as it can. Soon after diagnosis, this can include:

• Physical exams and brain studies. An electroencephalogram, also called an EEG, measures the brain’s electrical activity and may show the overall electrical disturbances in the brain. This may lead to the use of antiepileptic medications.