Families

Oro-facial-digital syndrome type 21 (OFD type 21) is a genetic disorder that is associated with oral anomalies, facial anomalies, digital anomalies and brain anomalies. It only occurs in males. OFD type 21 is caused by genetic alterations (‘mutation’) in a gene on the X chromosome. This gene is called ZRSR2. Females have two copies of the X chromosome. Hence, they have two copies of this gene. If females have a mutation on one of both copies of ZRSR2, they are expected to have no features of OFD type 21. However, their offspring, either male or female, have a 50% chance for inheriting this ZRSR2mutation. Males have only one copy of this gene. If a mutation occurs in this single copy of ZRSR2, a male will present with one or more features of OFD type 21. This disorder is very rare. Thus far, 8 boys from 6 unrelated families have been reported.