As such, this review will focus on submicroscopic duplications involving the MECP2 gene which may include clinically relevant nearby genes such as IRAK1, L1CAM and RAB39B. This review will document the 20-year history of research publications that have contributed to the current clinical understanding of patients with MDS and carrier females, as well as the biological function and relevance of the MECP2 gene in disease. This evidence concerns the gene L1CAM and myelodysplastic syndrome.