GJB1 and atypical Rett syndrome: However, a recent study substantiated the involvement of microglial Cx32 HCs in Rett syndrome, which is a neurodevelopmental disorder that affects young girls and is primarily caused by loss-of-function mutations in the X-linked MECP2 encoding methyl-CpG-binding protein 2 (MeCP2; Chahrour and Zoghbi, 2007).