Parents

Main clinical features
Mutations (changes) in RHOBTB2 can cause what is called developmental and epileptic encephalopathy (DEE). This is a severe brain disorder presenting at early age with seizures, developmental delay and movement disorders. Some patients show movement disorders without seizures.

A more extensive description of the clinical spectrum of RHOBTB2 mutations can be found in the section Families – Clinical characteristics.

Prevalence
RHOBTB2 mutations are rare. Due to a very limited number of cases (about 30) identified so far, it is difficult to predict the prevalence of the disorder. More studies are needed for a more accurate estimation of the frequency of RHOBTB2 mutations.

Inheritance
RHOBTB2 mutations are inherited in an autosomal dominant manner. This means that anyone carrying the mutation has a 50% chance of transmitting the mutation to future offspring. However, individuals with RHOBTB2 mutations are not known to reproduce.  To date, nearly all reported cases have resulted from de novo mutations. That means that the individuals carrying the mutation represent a single occurrence in a family and the mutation was not detected in either one of their parents. Therefore, parents of a child with a RHOBTB2 mutation usually have a very low risk of a second child with the same condition. The recurrence risk (probably <1%) is however greater than that of the general population since germline mosaicism in one of the parents cannot be excluded. This means that the mutation that is absent in blood cells of the parents, might still be present in their sperm or egg cells and therefore again be transmitted to future children. It is important to accentuate that this only occurs in rare instances.