This will be my attempt to try and explain the genetic of EB in terms that the average person can understand.
EB is an inherited condition.
Essentially, someone with EB is missing the "glue" that holds the skin together. By doing a biopsy, doctors are able to determine which "glue" a person is missing and therefore tell what type of EB they have.
Recessive forms of EB:
Those include:
All forms of Junctional EB
Recessive Dystrophic EB
One form of EB Simplex
And a newly discovered form of EB called Kindler Symdrome
In these types, the person with EB received 2 mutations, one from each parent. In recessive EB, it takes 2 copies of the gene that has the mutation on it to make EB. That is why the parents don’t have EB, they just have one copy of the gene. But when each of those copies is put together, that makes recessive EB.
With recessive EB, there is a 25% chance with each pregnancy that the baby will have EB.
Testing for Recessive EB
In testing for recessive EB, the lab will try and locate the two mutations in the child with EB. After those mutations are found, they will then look in the DNA of the parents to see if they too have the mutations. Once this is complete, you can use this information for prenatal testing in future pregnancies or if you have other children, have them tested to see if they carry one of the mutations so they will know for future reference when they grow up and have kids. Remember that with recessive EB, it takes 2 mutations to make EB, so if your other child(ren) just has one of the mutations, it means they don’t have EB, but carry a mutation than can cause EB.
Dominant forms of EB:
Those include:
Dominant Dystrophic EB
Most of the EB Simplex forms.
In these types it only takes 1 EB mutation to make EB. Typically one of the parents has EB and then passes it on to their child. In this case there is a 50% chance with each pregnancy that the baby will have EB.
Dominant forms of EB can also occur when a spontaneous mutation occurs at conception. No one knows why this occurs, it just does. There is nothing you ate, drank, did, or didn’t eat, drink or didn't do that caused this, it just happened.
Testing for Dominant EB:
In testing for Dominant EB, the lab will look for the mutation in the child. Once that is found, they will compare it to the DNA of the parents.
If they do not find the mutation in either parent, then this was a case of spontanouse mutation.
Visual Diagnose of EB
You may have found that many doctor will try to tell you what type of EB your child has just by looking at them. That is usually a very un-reliable way to diagnose a child with EB.
In my experience and observation of babies and children with EB, typically those with recessive forms of EB tend to start out milder in the beginning and get worse as they get older.
And, typically those with dominant forms of EB tend to start out more severe at birth and get better as they get older.
But everyone with EB is different and no two people will present the same way or progress the way the "experts" say they will based on the type of EB they have.
Biopsy and Genetic Testing:
Biopsy’s can be sent to either of the following places:
Beutner Labs, Inc.
3435 Bailey Ave., East Bldg. 2nd
PO Box 26
Buffalo, NY 14215-0026
716-838-0549
www.beutnerlabs.com
Stanford Dermatopathology Service
Department of Pathology - H2110
Stanford Medical Center
300 Pasteur Drive Stanford, CA 94305 650-723-6736 department of Pathology - H2110
E-mail: dermatopathology@lists.stanford.edu
http://dermatopathology.stanford.edu
Dermatopathology Office,
Gloria Magpantay: 650-723-6736
There are instructions on www.ebnurse.org on how to correctly do an EB biopsy.
Genetic Testing: (Currently only ONE place in the US does EB Genetic Testing)
GeneDx
207 PERRY PARKWAY
GAITHERSBURG, MD 20877
PH: 301-519-2100 • FAX 301-519-2892
www.genedx.com
