Ethmocephaly vs. Holoprosencephaly — What's the Difference?

Ethmocephaly is a type of cephalic disorder caused by holoprosencephaly. Ethmocephaly is the least common facial anomaly.

Holoprosencephaly (HPE) is a cephalic disorder in which the prosencephalon (the forebrain of the embryo) fails to develop into two hemispheres, typically occurring between the 18th and 28th day of gestation. Normally, the forebrain is formed and the face begins to develop in the fifth and sixth weeks of human pregnancy.

A rare cephalic disorder characterised by the absence of a nose and the presence of a proboscis between the eyes

(teratology) A congenital disorder involving insufficient division of the lobes of the brain during fetal development, resulting in skull and facial deformities ranging from minor cleft lip problems to cyclopia, in which a single eye develops where the nose would normally be.