When children as young as Will have these types of eye problems is one of a few things. It can be from being born premature, trauma at time of birth, or genetic mutation. In Will's case he was actually born a week late through induction, and there were no issues at time of birth that would cause a trauma injury to the eye. This left one conclusion; genetic mutation.
FEVR (familial exudative vitreoretinopathy) and Norrie disease are the 2 genetic diseases known to cause these issues. The only way to confirm this diagnosis is through genetic testing, and even then they are discovering new mutations daily.
They can test through drawing blood, or mouth swab. They start by testing the patient for the 3 different genes most commonly associated with FEVR and Norrie; FZD4, LRP5, and NDP. Depending on which it comes back as the parents are then tested from there. The genetic testing takes a minimum of 4 weeks and usually more. If someone has one of these genes there is a 50/50 chance the child will be affected.
FZD4 - this gene is also called frizzled 4. It produces frizzled 4 protein which plays a critical role the development of the retina. Mutations or deletions in this gene is known to be associated with FEVR. From all the known mutations thus far in this gene they are associated with FEVR symptoms only. It is my basic understanding that this can be inherited from either parent.
LRP5 - This gene just like frizzled 4 is critical in development of the retina. It also plays a key role in bone density. Mutations in this gene not only can cause FEVR but also Juvenile Osteoporosis and syndromes associated with low bone density. Again it is my understanding wither parent can pass along the mutation.
NDP - This gene produces the norrin protein. The norrin protein plays a critical role in development of the retina and other body symptoms. Mutations in this gene can cause x-link FEVR or Norrie disease which can then affect multiple body functions. This is a x-linked mutation where women are carriers and men can be affected.
Will's Mutation and Our Genetic Story
Before receiving Will's genetic results Jon and I as well as family prayed endlessly that he would not have Norrie. Obviously out of all the possible results NPD and Norrie disease can have the greatest impact. When Will's results came in it was approximately 8 weeks after they drew his blood. Hearing the results was like being hit by a truck! I furiously scribbled information on a notepad. That day is a vivid memory that I will never forget.
Ultimately Will's mutation is on the 400th letter of the NDP gene. The 400th letter should be a G but in Will they found a C in it's place. This specific mutation has never been seen before. Because we have no point of reference we have no idea how significant of a mutation this is and how great an impact it will have for his future. Similar mutations have been found. In one case there was a C instead of a G found at the 338 letter which resulted in FEVR symptoms only. In another similar case a completely different letter was found at the 399 letter which resulted in a classic Norrie diagnosis. We have no idea which will play out for Will.
As soon as we had Will's results It was my turn to be tested. NDP mutations result in X-linked FEVR or Norrie. That means it was either a spontaneous mutation in Will or it came from me. My results took almost 8 weeks to come back and as we expected I also had the mutation. The reason women aren't affected is because we have two X chromosomes. The one X has the mutation represented in red and the other X is unaffected. Because as a woman we have the normal chromosome to fall back on we develop normally. Will had a 50/50 chance of inheriting my mutated X and as it turned out he did. Because he only at the mutated X he then has clinical symptoms. If we had a girl she would have been fine however she would have had a 50/50 chance of being a carrier just like me. From there my sister was tested and came back negative for the mutation. This shows it truly is 50/50.
Future Children?
This changed everything for us. You have this idea in your head of a happy little family. Father, mother, son, and daughter. The picture perfect family. My mutation being what it is makes the risk of passing this terrible disease on too high. Our options for future children are limited to invitro with genetic testing, or adoption. These things bring about a whole nothing complicated decision. Which then leads to even more. At the age of 28 and 30 my husband and I had to discuss not having more children not by choose. You then have to discuss even more uncomfortable topics such as vasectomy's vs. tube tying procedure....
I wouldn't wish this disease on anyone. If you're not overwhelmed enough by your son being blind and the numerous doctors appointments. The realization that you gave him the mutation and you're no longer able to conceive naturally without passing it on again... These are things no one should have to go through and the emotional complexity of it all. There is no easy way through this journey, I do my best to take it one day at a time.
Just a couple of mutants!
