Conclusion
This is one of only a small number of natural history studies examining the clinical course of a cohort of patients with PLP1duplications within the context of a validated functional disability scoring system. This study is unique in that it is limited to subjects with PLP1 gene duplications. This study demonstrated many commonalities to other studies that have characterized the features of PMD and other PLP1-related disorders but also provide significant new insights into the evolving story that marks the natural history.