POU4F1 and paroxysmal nonkinesigenic dyskinesia: Pnkd (paroxysmal non-kinesigenic dyskinesia) has three RefSeq isoforms (NM_019999, NM_025580 and NM_001039509, Fig. 9eII-eIV), all of them seem to be expressed in both RGCs and retina, but only one of them is regulated by Brn3a (NM_019999, Fig. 9eII).