Should I Test My Children?

On one of the online HNPP support groups I am part of, one member asked us this question:
Should I test my children for HNPP?
She had recently been diagnosed and was wondering if she should have her children tested as well and how to protect them if they have it, but was it wise if knowing could harm them emotionally, worrying about it and their future.
I was one that replied mostly because it is a question I am mulling over myself.  Here is my reply.

"Thank you for posting this question.  This is something I am dealing with at present as well.  I have five children and my oldest is nine.  We learned about HNPP because my oldest who was then six lost the use of her left hand and part of her arm suddenly and instantly from doing NOTHING at all.  She was simply resting on her elbows as she listened to a story and pop, her hand was paralyzed.  Talk about feeling like you don't know how to protect your children.  I feel this very strongly as well.  It is a delicate balance that I haven't yet learned how to manage, although I think I am getting better.  I am a big advocate for being open and knowing what you are dealing with.  There was a whole set of cousins that knew about this disease being in the family but never shared that knowledge.  I know it is very personal for some people but had we known it could have helped us a lot in diagnosing what was wrong with her.  It took over a year, another injury, and several tests before she was diagnosed.  I am not bitter about it, I just push for openness where it might concern or help others.  That being said, I have yet to test any of my other children.  Originally, I wanted to get them all tested.  I felt it would be important as their mother when planning what extracarricular activities would be safer for them and hopefully teach them to be cautious with their body without them feeling like they have to live in a bubble or creating a hypochondriac. 

Every doctor I have discussed this with has discouraged me from having the others tested for a few reasons.  

1) The insurance won't cover the blood test because it would be exploratory rather than "necessary."  

2) It would be violating the rights of my children to choose for themselves if they want to know or not (this reason took me quite a while to understand and I am still not sure if I agree with it) 

3) Just having them diagnosed with this disease, despite having symptoms or not, will make it harder for them to get both life and health insurance.  

I still want to know, but I was advised by our pediatric neurologist to only test them if symptoms arise in the others.  I guess I am waiting for this or I just still can't decide.  As far as protecting my HNPP daughter:  This is something that I am still working out.  My husband, whom we learned has HNPP as well, is for letting her live her life and just dealing with the issues as they come.  I am more cautious and want to prevent as much damage as possible but still don't want her to miss out on being a "regular" kid.  Because she has had some serious issues with it at such a young age the neurologist feels she has a severe case; this pushes me even more toward caution.  I look at it like we need to preserve her function for as long as possible by preventing any injury we can for as long as we can.  I basically encourage her to be an underachiever as far as physical activity.  We have to watch out for pressure, repetition, and stretching (basically everything), so I tell her if it pulls: stop doing it, if it hurts: don't do it, change your position a lot and don't rest on anything, and don't be aggressive (her second injury was from playing boxing on the wii).  Hopefully overtime she will learn her limitations and we are just cautious.  She recently started taking violin and her teacher stressed position, position, position.  She can't hold the violin that way safely or her wrist.  It was at this point that I explained her disease to her teacher.  We didn't take her out of violin and she is able to play, she just plays it like a cello.  I try to help her do all that she wants to do but sometimes we need to do it differently.  She understands she can never push herself to become an athlete, but I still let her participate in sports but it is only for fun and exercise rather than to achieve.  I may be wrong but this is where we are right now.  I am anxious to hear the advise others in the group have to offer us as well.

- Jerusha       

Annual Neurological Checkup

Checkup:

I took our oldest in for her annual exam with the Neurologist at the Children's Hospital. They did another nerve conduction test (electromyogram or EMG) on her extremities. The first time she had this done was a few years ago during all her exploratory testing to determine what was wrong with her. I was promised that she would be medicated for the test. This is a test where they put a needle into a muscle and send a shock, then they measure the response time and strength from the nerves. My daughter is very afraid of needles so I was grateful she was going to receive medication for it. My husband was able to go with her for it but when they finally set her up for the test, the doctor said that there was not enough time to administer and wait for the medication to take effect so they had to do it unmedicated. He chose to go ahead with the testing since we had waited so long to get an appointment for it. It was a very traumatic experience for her. When my husband told me about it, I was very angry about how it was handled. This was just part of my poor daughter's trial in the effort to get her mystery problems diagnosed. They wanted to get another conduction test done because it has been a few years and because their readings weren't very accurate due to her distress during the last one. The medication was a priority this time and it did go much smoother thankfully. We also had a much less in depth EMG done on our second oldest who is six to see if there were any abnormal nerve responses. There is a 50% chance that each of our children have the disease but our oldest is the only one who has expressed any symptoms and the only one tested for the disease. Testing her, our second, provides us with a base line to work from should she develop symptoms later and may show if there is any damage. It will not confirm whether she does or does not have HNPP but if there is any nerve damage, it is a possibility.
The Results:
Our oldest showed evidence of nerve damage on every nerve tested. Her arms, wrists, legs and ankles were all tested. Not good at only 9 years old but things could be worse. She appears to be functioning normally right now and her only recent issue was very mild. She woke up with one arm much weaker than the other. She could move everything as she should but it took a lot more effort. Thankfully this problem was gone by the end of the day. We have her sleeping on a memory foam mattress to reduce pressure while she sleeps but it is not a guarantee.
This disease is so hard to monitor. Nerves can and are being injured during normal daily activity but you don't know until enough of the nerves in the bundle get damaged that the others can no longer compensate for the difference. Then we see it, when normal function is effected. She had a period of over a year where she was incontinent. Her bladder muscles were very weak. Very unusual in young children who are well beyond toilet training. It only made sense to me that it was HNPP related. Muscle weakness onset with no apparent injury and then the eventual "healing" on its own. We went to several doctors about this problem too and none could agree on a cause or found something that would help. Some thought it might be related, some said it wasn't, and no one said it was for sure due to HNPP. Another trial in having a rare, lesser studied and lesser known disease.
Our second child's results were that she did have some nerve damage in her wrists. Similar to carpal tunnel at six years old. Not normal but not a confirmation that she has it, probably does in my opinion.
Genetics:

I understand genetically how each of our children have a 50% chance of having this disease. It is not one that can be a recessive gene, you cannot be a carrier. You either have the needed gene(PMP22) or you don't. Normal individuals have two PMP22 genes. This gene affects the myelin coating or sheath surrounding and protecting the nerves. Those with CMT have more than two, those with HNPP are missing one. The non affected parent gives one PMP22 gene, and the other parent has a 50% chance of giving the gene or not giving it. Thus there is a 50% chance that you will get that needed second gene. If you don't get it, you have HNPP. This being said, there seems to be a much higher percentage in my husband's family. His father, who has been tested and confirmed to have HNPP, had four children. All four show symptoms of HNPP. Of these four, two of them had children. The oldest children in these two families thus far have expressed symptoms of HNPP.
In My Opinion: It seems to be difficult for doctors to accept unusual symptoms from HNPP patients being due to HNPP. Not only is it rare, it is also rarely diagnosed due to its hugely varied symptomatology, varied degree of severity and lack of knowledge among the medical community. My husband visited several doctors over the years for various problems that were considered "mysterious" in some way and not only was the condition HNPP not considered, it was completely unknown to them. He was never led to a neurologist and there are many others with mild enough symptoms that they never mention them to a doctor. We were only led to the knowledge of it in our family through our daughter's problems, and even then I feel we were lucky we received the correct diagnosis despite it taking a year. Her neurologist was familiar with it. Even with this knowledge we hit stumbling blocks with doctors who just don't know enough about it to accept what we say. They still want to eliminate all other possibilities for having the trouble they do before reaching the conclusion that the only thing you can do is leave it alone until it starts to heal and then mild occupational or physical therapy to regain as much movement as you can. I appreciate doctors and all they are able to do but they are also part of a frustrating cycle at times. Hopefully in years to come it will get better as more information becomes available to all of us.