In my campaign we have a group of five DW Marines and one female player playing an Inquisitor/Psyker transplanted in from the Dark Heresy setting.
In DW Genestealers have the Trait "Tyranid" in the Dark Heresy setting they have the Trait "From Beyond". These two traits are essentially the same; just different names for the same benefits. What ever it is called the trait states, in part: "It is immune to Fear, Pinning, Insanity Points and Psychic Powers used to cloud, control or delude its mind." Preceding taken from page 330 of the Dark Heresy Book.
In your opinion would creatures with this Trait be immune to the Telepathic Psychic Power "Psychic Shriek" found on page 180 of the Dark Heresy book?
I probably ought to cross-post this in the Dark Heresy forum as well.