GENETICS OF EB
EB is caused by genetic variants. Disease-causing variants in more than 20 genes are associated with EB. These genes contain the information that is translated into proteins such as keratins, collagens, laminins, and integrins, which are present in the skin and ensure its integrity and resistance. The variant in a gene affects the correct function of these proteins. EB can be inherited in one of three ways: autosomal dominant inheritance, autosomal recessive inheritance, and de novo inheritance.
AUTOSOMAL DOMINANT INHERITANCE
One parent is affected and passes the altered gene on to their child. There is a 50% chance that any child of theirs would be born with EB.
AUTOSOMAL RECESSIVE INHERITANCE
Both parents are unaffected but are carriers of EB. For any child of theirs to be born with EB, the child would have to inherit the disease-causing variant from both parents. There is a 25% chance of this occurring.
DE NOVO INHERITANCE
A disease-causing variant happens spontaneously for the first time in a person. In this situation, having a second child or more with EB from the same parents is very rare. On the other hand, the person carrying a de novo variant has a 50% chance of passing it (and EB) on to their children.