Holoprosencephaly

It is a spectrum of fore brain disorders characterized by different degrees of frontal lobe fusion.

Alobar holoprosencephaly is when their is no interhemispheric fissure, single ventricle and basal ganglia and thalami are fused.

Semilobar holoprosencephaly is when the interhemispheric fissure is present posteriorly, basal ganglia, hypothalamus, caudate and thalami may be partially fused and there are partial formation of occipital and temporal horns.

"The face predicts the brain"

That means one can suspect it from various midline facial defects athat are often present including-

midline cleft, central incisor, absent superior frenulum, single nostril.

Seizures, dystonia and endocrine dysfunction is common. Posterior pituitary dysfunctions are more common than anterior pituitary deficiencies.

Workup includes high resolution chromosomal studies and HPE genetic mutations, electrolytes, cortisol, TSH, ACTH.

Recurrence risk is 6%. First trimester USG and fetal MRI can pick up holoprosencephaly.