Eea1, or Early Endosomal Antigen 1, is a key protein in endosomal trafficking [4]. It plays a crucial role in the homotypic fusions of early endosomes, which are the main sorting station on the endocytic pathway [1]. Eea1 binds to the PI(3)K product phosphatidylinositol-3-phosphate and serves as a Rab5 effector, linking PI(3)K function to Rab5 regulation of endosome fusion [2].

In Rett syndrome, a neurodevelopmental disorder caused by loss-of-function mutations in MECP2, Mecp2-deficient neurons lack homeostatic synaptic plasticity, likely due to reduced levels of Eea1. Expression of Eea1 in these neurons restored homeostatic synaptic plasticity, suggesting Eea1 as a novel target for intervention in Rett syndrome [3]. Also, mutations in Eea1 are associated with allergic bronchopulmonary aspergillosis (ABPA). Variants in Eea1 affect the phagocytosis of Aspergillus fumigatus conidia and the acidification of phagolysosomes by human macrophages, providing new insights into the susceptibility to this disease [5].

In conclusion, Eea1 is essential for endosomal trafficking and endosome fusion. Its dysregulation is implicated in diseases such as Rett syndrome and ABPA. Studies using relevant genetic models like Mecp2 - deficient neurons have revealed its role in maintaining synaptic plasticity and in the context of ABPA, enhancing our understanding of disease mechanisms and potential treatment targets.