idiopathic/sporadic
inherited as dominant, recessive, or sex-linked
chromosome deletion in band 14q22-23 with associated polydactyly, as well as a deletion in 7 p15.1-21.1 associated with cryptophthalmos/anophthalmos
trisomy 13-15
genetic deletions involving SOX2, SIX6, and STRA6, with many new microdeletions being reported, including within PAX6, RAX, and SMOC1.
maternal infections during pregnancy (ie, rubella, toxoplasmosis)
often associated with syndromes with craniofacial malformation (Goldenhar syndrome, Hallermann-Streiff syndrome)