Discovery of the new CHARGE gene

August 31, 2004

As usually happens, the parents got the word out about the gene

first. I am delighted that Dr. vanRavenswaay has logged on and made

comments.

After talking to Sally Prouty, I think it is important to make a few

things clear. First, this is the FIRST gene to be isolated but it

undoubtedly will not be the last. Let me illustrate by telling you

about my experience with Usher Syndrome (another deafblind

condition). The first gene was discovered in France. When other labs

around the world started checking their own patient samples, they

could not find the gene. Later, 2 more genes were discovered on a

different chromosome. It turned out that the French gene really was

a French gene. By that I mean that the only people who had that gene

came from or were descended from people who lived in a particular

area in France. Now we know of 11 different genes for Usher Syndrome

and more will undoubtedly be discovered.

CHARGE is a very complex syndrome, much more so than Usher. Many

organs are affected and each one can be 0-100% affected. This means

that lots of combinations exist. Dr. vanRavenswaay works with Dr.

Admiraal who is an ENT interested in the vestibular system of these

children. All 17 of the children studied had vestibular

abnormalities. [by the way, I know of kids who meet the criteria of

CHARGE who do not have vestibular abnormalities.] What I am getting

at is that they have looked at a particular population of CHARGE. Of

their 17, 10 had an abnormality of the CHD7 gene. This means that 10

did not. Therefore, there will be more genes discovered later.

Many of you have already contributed samples to the Baylor study. I

am sure that these will be screened for the reported gene.

The Dutch discovery of a new gene for CHARGE is indeed exciting. It

confirms what Meg Hefner, Bonnie Pagon and I have been saying for 20

yr. We believed that CHARGE syndrome was genetic but it was just a

matter of time until this was proved. This also puts to rest the

issue of syndrome vs. association since the first gene has been

discovered. Now other geneticists will come on board, too, using the

term syndrome.

What does this mean to the families? In other words, so what? What

will knowing that your child has the gene do for your child, your

family and your child's future?

The most immediate benefit could potentially be prenatal diagnosis

for future children IF the child definitely has the gene AND the

parents have also been checked. If the child does not have the gene,

then prenatal diagnosis would not yet be available. As to the

child's medical and educational problems, we will need to look

carefully at the medical and educational histories of the children

who have the confirmed gene change and, particularly if there are

older children or adults, we would be able to say something about

what to expect in the future. In other words, it does not change

what we are doing right now except to have an earlier diagnosis.

Does finding the gene also mean finding a cure? NO. This is a long

process. First, researchers have to figure out what the gene does.

Dr. vanRavenswaay has said that it appears to be involved in early

development. That has been what geneticists have postulated for 2

decades now, so that makes sense. If this is a gene that acts in

early development, there is now and for the forseeable future no way

to correct the gene abnormality. Much more research needs to be

done. This means years not weeks or months.

For those of you that would like more information about chromosomes

and genes, check out

http://ghr.nlm.nih.gov/

and look under Help Me Understand Genetics. CHARGE is not yet one of

the diseases referenced in this new online service because no genes

had been discovered.

Hope this helps.

L.H. Davenport, M.D.

Pediatric Geneticist/Developmental Pediatrician

slhdaven@...

August 31, 2004

Dr Davenport-

Thank you for clarifying all of my questions -- before I even asked :-)

! We all know that this finding is significant and important. But how

and why it is important is what we don't know. You have helped me to

understand that -- in a way that I can explain to family and friends.

It's exciting to be privy to the news as it occurs. And I think we can

all be excited about this finding. But we do need to understand that it

is just the tip of an iceberg that is still very much submerged. But,

heck -- yesterday we couldn't even find the tip of the darn thing!

Michele W

Aubrie's mom 6 yrs

August 31, 2004