Delleman syndrome is described by orbital cyst or periorbital skin appendages, which might or might not be correlated with anophthalmia or microphthalmia, major cerebral malformations, and focal dermal hypo- and aplasia. The disorder was found to be more frequent in males with a male to female ratio of 19:9. Delleman syndrome is diagnosed through magnetic resonance imaging (MRI) which may show hydrocephaly with a thin cerebral cortex and misshapen ventricles. It was suggested that minimal diagnosis criteria should include a central nervous system cyst or hydrocephalus, orbital cyst or microphthalmia, and focal skin defects.

The majority of Delleman syndrome cases are sporadic, however, few cases are found to have a family history of ocular abnormalities. Mosaicism for a lethal gene may possibly trigger this syndrome.