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What is PCDH19 Epilepsy?

PCDH19 Epilepsy is a disease with a wide spectrum of severity in seizures, cognitive delays and other symptoms, which are all caused by a mutation of the PCDH19 gene on the x chromosome.  Males with the mutation, who will be largely unaffected, will pass the mutation onto 100% of their daughters and none of their sons.  Women with the mutation have a 50% chance of passing it to their daughters and will pass it to 50% of their sons.  Recently, scientists have discovered some unaffected females and are studying to learn what is protecting them from the disorder. Mosaic males are also affected, but so far very few males have been diagnosed.

You can learn more about the basic genetics related to PCDH19 by watching our Educational Video Series.

It is now suspected that 1 in 10 girls that begin having seizures before the age of 5, may have PCDH19 Epilepsy.  
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What Are The Symptoms Associated
With PCDH19 Epilepsy?

Seizure Clusters

The most consistent feature of this disease is seizures that come in clusters and last for days or weeks at a time and do not respond well to available medications.

  • The first seizures usually occur between 3 months and 3 years of age with an average of 9 months.

  • At first, the seizures usually occur in the setting of a fever, and later they come with no known trigger.


  • Sometimes loss of hearing, and loss of skills are experienced after seizure clusters.


  • Seizures are often drug resistant and difficult to control.

Seizure Types

The most common seizure types for PCDH19 Epilepsy:

  • Generalized tonic-clonic.

  • Tonic, clonic.

  • Complex partial.

  • Atypical absence.

  • Atonic drop

  • Myoclonic seizures

These seizure types may be accompanied by rapid oxygen desaturations and cyanosis.


It is estimated that about 70% of PCDH19 patients have intellectual disability of varying degrees, ranging from mild to severe. The course of development usually follows one of three paths:

  • Normal development from infancy, but with regression after seizure onset.

  • Normal development and intellectual ability from
    birth without regression.


  • Delayed from birth and remains delayed through adulthood.


  • Autism spectrum disorder or autistic features (estimated at 60%)

  • Behavioral problems.

  • Aggression.


  • Anxiety.

  • Obsessions (OCD).

In adolescents and adults, depression, bipolar, schizophrenia, psychosis and other mental illness have been reported.

Other PCDH19 Symptoms

That Can be Present:

  • Sleep disturbances, trouble falling and/or staying asleep.


  • Ictal Apnea – Many individuals also stop breathing during their seizures and have rapid and sometimes prolonged oxygen desaturations.


  • Hypotonia (low muscle tone)


  • Fine and Gross motor deficits


  • Language delay or non-verbal


  • Sensory integration issues


  • Dysautonomia


  • Delayed tooth eruption seems common.


  • Issues with constipation (whether due to disorder or medications) are very common.

Please note that this site should not and does not replace medical information or advice from health care professionals.
If you live in the United States, depending on the associated symptoms that the person with PCDH19 experiences, as well as your state's eligibility criteria, you may qualify for support through your state. The guide linked below can serve as a starting point for helping you understand & navigate available insurance and waiver programs in your area. 
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