Typical findings of holoprosencephaly in its alobar form as it's supposed to be imaged in the first trimester. 

Holoprosencephaly may be associated to other midline defects and may be part of an aneuploidy such a trisomy 13 (Patau's syndrome).

Lack of prosencephalus division at a later stage either leads to semilobar holoprosencephaly or lobar prolosencephaly. The latter may be a challenging differential diagnosis to septal agenesis.