UBE3A and nervous system disorder: While the functions of RLD1 and RLD3 remain unknown, the RLD2 of HERC2 has been observed to regulate E6AP autoubiquitylation, another HECT E3 ubiquitin ligase whose malfunction is connected to the neurological disease, Angelman syndrome (Kishino et al. 1997; Kühnle et al. 2011).