MECP2 and Rett syndrome: In particular, this has been illustrated in the few studies published from Iberoamerican populations: Lima et al. (Lima et al., 2009) in a study of 105 patients with RTT from Brazil found MECP2 variants in 60% of them, while Vidal et al. (Vidal et al., 2017) in over 1,500 patients from Spain confirmed the diagnosis of RTT in 30% of them, and found another diagnosis in a similar proportion using different molecular strategies ranging from single gene to exome sequencing.