MECP2 and atypical Rett syndrome: Clinically, efforts are ongoing to develop strategies for inducing reactivation of the inactive X in patients–for instance, targeted X-reactivation methods are underway to help young XX individuals affected by Rett syndrome, who carry an active X chromosome harbouring a mutated allele of the MECP2 gene and an inactive X chromosome harbouring a wildtype allele [151,164,165,166].