What is the incidence of SCN8A cases? While only about 90 cases have been documented so far worldwide, research indicates that SCN8A mutations could account for roughly 1 percent of epilepsies in young children. As such, the number of identified cases is expected to grow rapidly. And as the numbers grow, so does our potential to gather essential data to fuel the needed research to bring real answers to all our questions and hopes.

 

What is the prognosis for children with SCN8A? This is largely unknown although in our small family group of about 40+ children, there are several pre-teen and teen-aged children. There is only one confirmed case of an adult with an SCN8A mutation who has controlled seizures and some intellectual disabilities. Yet with the cause of nearly 2/3 of epilepsies unknown, based on tests and information used as recently as three years ago which excluded SCN8A, there is reason to believe there may be older children and adults with SCN8A mutations. Sadly though, SCN8A has been linked to a high incidence of sudden death (SUDEP), so it is unclear what the overall prognosis is and why some children succumb.

 

Are treatments available? Yes and no. There are many anti-epileptic drugs (AEDs) which can and do help children with SCN8A get some control of seizures. In our own recent survey gathering information on 20 of our children, we found wide variation in the level of seizure control:

 

Level of Seizure control

• Little (multiple daily)                  20.0%

• Some (not daily)                       40.0%

• Good (infrequent)                     30.0%

• Very Good (very infrequent)     10.0%

 

 

While it is clear a large number of kids do not yet have seizure control, there is also the sad reality that far too little is known about conditions and characteristics of our children and what is likely to make specific drugs either effective or highly toxic. We already know that there is a wide variation in which AEDS work or harm different children with SCN8A mutations – in some cases the same medication can be highly effective in controlling seizures in one child while for another is is highly toxic or just doesn't work.

 

The ketogenic diet and CBDs (or cannaboids oils) have also frequently been prescribed – again with uneven results.

 

Clearly, research into better understanding when and which AEDS or other treatments might be most effective for different children is one of the highest priorities for research into how SCN8A works – and how to improve the condition of our children. 

 

What are some of the related medical challenges these children experience?  Many of our children experience other complex and even life threatening medical conditions. Again, our survey of 20 children in our family group revealed the following:

 

• G-tube (feeding tube) dependent              50.0%

• Pulmonary/unsafe swallow                       40.0%

• Scoliosis                                                     30.0%

• Visual (cortical blindness)                        25.0%

 

• Other common medical Issues

  • Reflux

  • Chronic constipation

  • Laryngomalacia

  • Sleep irregularity

  • Myelin disorder

  • Dystonia

  • Liver function (side effect of Valproate)

  • Hyperplasia of gums (side effect of Phenytoin)

 

How do I find a qualified doctor – or assess whether current doctors are the right fit for my child? This is a tough area since we all feel so reliant on doctors to make some sense of this mysterious disorder – and know what’s best for treating our children.

 

Dr. Michael Hammer, the first to identify the SCN8A gene in his own beautiful daughter, is building a wonderful interactive website (discussed further below) which will soon be providing more structured and specific guidance on this issue – including recognized neurologists with established expertise who agree to be accessible for consultations with doctors treating SCN8A for the first time.

 

But in the meantime, here are some of our thoughts:

 

First – trust yourself and your own instincts – absolutely no one knows your child better than you do – and it is critical to be observant and proactive in tracking and reporting changes in your child’s condition to your child’s neurologist – and possible effects of different medications. Speak up – trust yourself.

 

That being said, you definitely need an experienced – and conscientious – neurologist, if not further sub specialist,  including an epileptologist and a genetic neurologist. Given the extremely small number of identified cases, depending on where you live, you probably can’t hold out for a doctor who has already been treating other SCN8A cases – there are just so very few and certainly not close to all the families constantly being diagnosed. But you should be confident that your doctor is taking the initiative to remain current with the continually emerging literature on SCN8A. Even though clear dispositive answers have not yet emerged, this developing information is critical for your doctor to follow if he is to make the most informed treatment decisions for your child. Again – ask questions and trust yourself.

 

Also we have found coordination of care by the many specialists Elliott sees is extremely important (e.g. GI and pulmonary). We struggled with this for some time – and finally came upon a godsend when we found a dedicated hospitalist who runs a Complex Care program at Children’s Hospital here in D.C. Sometimes hospitalists focus only on in-patient cases, but we have been lucky to find someone who also is a ready resource and coordinates care for all our out-patient appointments as well. It is certainly worth asking to see if there is a program like that at your hospital.

 

Finally, not everyone would qualify or be willing to go this route, but we have found the hospice program to be a valuable resource in helping stay on top of Elliott’s condition on an ongoing basis with experienced RN visits to the house – and available on call 24 hours a day. Elliott has rather severe respiratory complications due to his extremely low tone – and the array of equipment we have at home combined with the knowledgeable eye of his hospice nurse, had helped keep Elliott out of the hospital for nearly 9 months – after 6 consecutive visits over a two month period last summer. Families should understand that hospice for children is far more flexible than with adults – while a life threatening condition must be present, enrollment requires no abandonment of treatment – so our view was we gave up nothing and gained excellent support by enrolling Elliott in a hospice program. And happily Elliott has been in the program over eight months now. Children have been in the program for years – and some even “graduate" when their condition is so improved to reduce an earlier high risk that qualified them for the program.

 

What are my risks of having another child with the same mutation? This is of course the domain of your neuro-geneticist and genetic counsellor. But because this is such a common question and limited discussion of the process of understanding the risks exists, here is how Gabi and John, Elliott’s parents, approached the issue:

 

The best information we could get indicated that Elliott’s genetic mutation was "de novo,” meaning it was not inherited from either John or myself but occurred spontaneously in Elliott. John and I have both undergone genetic testing for Elliott’s SCN8A mutation, and they did not find it in us. However, there have been other parents who did not think that they had it, and yet they had more than one child with an SCN8A mutation. The most likely explanation is something called genetic mosaicism, in which the genes in one part of your body can differ from the genes in other parts of your body. In this scenario, the cells in most of our body (including our blood) might have the normal, healthy version of the SCN8A gene, but one of us might have the mutated version in our reproductive organs (called gonadal or germline mosaicism). If that were the case then we could pass the mutated version on to multiple children, even though a blood test would say that’s not possible.

 

Gonadal mosaicism is rare, but not rare enough to calm our nerves. We had hoped to rule it out before we started trying to have a second child, but unfortunately, gonadal mosaicism is very difficult to test for. We did what testing we could, but we were not able to eliminate the possibility completely.

 

In reality, the only way we could tell whether our next child would have this mutation was to get pregnant, wait until almost halfway through the pregnancy, and then test the fetus itself by doing an amniocentesis. And that is what we did, which made the first 4.5 months of the pregnancy incredibly difficult. The “what if” was constantly in the backs of our minds, even after I started to feel the baby kicking. At week 18, we had the amniocentesis. Several tubes worth of amniotic fluid were drawn from the amniotic sac and sent out for genetic testing. We were told that the wait could be up to three weeks, but luckily the results back came after only a week and a half: Baby #2 does not have the same SCN8A mutation as Elliott.

 

That testing did provide some relief, but we still have concerns. For one thing, while we are fairly confident that Elliott’s SCN8A mutation is the source of his troubles, we can’t be certain. Because so little is known about the mutation, it could very well be that his SCN8A mutation is harmless and the real culprit is still unknown to us.  Or, it could be that his SCN8A mutation really is damaging, but that he also has a second harmful mutation that we don’t know about that is causing some of his more extreme health issues. Both of these scenarios are unlikely, but possible. And even if Baby #2 is free from whatever it is that Elliott has, that just puts us in the same boat as all other expecting parents.  The testing we’ve already had done can rule out a few issues such as Down Syndrome, but otherwise, this baby is at the same risk as any other for anything that can afflict a kid – genetic or otherwise – from autism to leukemia. All of those things are farfetched, but we’ve been hit by lightning before and we still worry that we might somehow have a second sick child. Once bitten, twice shy.

 

Recently a family working with a geneticist at London’s Great Ormonds Street Hospital (GOSH) reported on a newer and earlier emerging approach. They have started using a new screening technique that is less invasive and can be done as early as 9 weeks. Blood from the baby passes through the placenta into the mother’s blood and a small trace of this blood can be used to locate any mutations on the SCN8A gene. So they simply take a blood test from the mother before pregnancy and then again after 9 weeks. GOSH is now preparing for the first use of this test for SCN8A. This option is clearly just emerging, but worth discussing with your geneticist.

 

Additionally, we recently learned about an additional option other than prenatal diagnosis.  It is possible to do IVF and preimplantation genetic diagnosis (PGD), which can be costly and may not be covered by insurance.

 

How/Where to Get Help AND Help Accelerate Progress

 

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TAKE ACTION to HELP – YOU Can Make a Difference

• Participate in Hammer Registry: Dr. Michael Hammer, a genetic researcher who identified the first human case of SCN8A in his own daughter, has devoted himself to further research and networking of SCN8A families. He is in the beta stage of developing a powerful and exciting new tool which will be an open resource for not only families but also clinicians and researchers. A central component of the resource will be case histories of as many SCN8A cases as possible which will be collected and published on a de-identified basis for an interactive website.

 

The single most important thing you can do as an SCN8A family to help advance understanding of SCN8A is to participate in this database, sharing information on the condition, treatments and outcomes of your children.  Please consider participating; contact him directly at mfhammer19@gmail.com.  www.scn8a.net

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