Given i) preeclampsia is a heterogeneous disorder with multiple molecular subclasses [17] ii) despite this, the placenta is a key driver in the pathogenesis [26,346,347] iii) placental HDAC9 is down-regulated in preeclampsia [34,40] and iv) HDAC9 is an expansive modulator of related cellular processes including placentation, immunity, angiogenesis, and GPCR signaling [34,40,42,46,86,131,167,212,348], more comprehensive explorations are warranted. Here, HDAC9 is linked to preeclampsia.