A craniofacial developmental disorder in which there is a failure of the prosencephalon (embryonic forebrain) to develop; severe forms may cause cyclopia. The genetic basis is diverse: holoprosencephaly-1 (HPE1) maps to 21q22.3. HPE2 is caused by mutation in the SIX3 homeobox gene, HPE3 is caused by mutation in the sonic hedgehog gene, HPE4 is caused by mutation in the TGIF gene that encodes TGFβ-induced factor. HPE5 is caused by mutation in the ZIC2 gene that encodes zinc finger protein of the cerebellum-2. HPE6 maps to 2q37.1. HPE7 is caused by mutation in PTCH1 (see patched). HPE8 maps to 14q13. HPE9 is caused by mutation in the gli2 oncogene.
http://www.holoprosencephaly.net Website created by parents of children with this condition.