POMGNT2 and cobblestone lissencephaly: Loss of function (LOF) variants in either POMT1–2 or POMGNT2 cause Walker Warburg Syndrome (WWS), the most severe dystroglycanopathy that is associated with profound brain and eye malformations including cobblestone lissencephaly, hydrocephalus, cerebellar hypoplasia, and retinal defects [22–24].