Split hand split foot nystagmus is a rare congenital syndrome characterized by split hand and split foot deformity and eye abnormalities, especially nystagmus. It is thought to have an autosomal dominant mode of inheritance. Currently, the underlying genetic defect has not been identified. The outlook for children with this condition is good.

Split hand split foot nystagmus is thought to be inherited in an autosomal dominant fashion. A person with an autosomal dominant condition has a 50% chance of passing the condition on to their children.

Sometimes a person is the only one in their family with the autosomal dominant disorder. One explanation for this is that the person has a de novo or new mutation. De novo mutations refer to a change in a gene that is present for the first time in one family member as a result of a mutation in the mother’s egg or father’s sperm, or in the fertilized egg itself.

In addition, there have been a couple of case reports where unaffected parents had more than one child with split hand split foot nystagmus. It is thought that this may have been due to germline mosaicism. In germline mosaicism, one of the unaffected parents has the disease-causing genetic mutation in some of his/her eggs or sperm only.