Drosophila Multiple Epidermal Growth Factor-like Domains 8 (dMegf8) is a homolog of human MEGF8. MEGF8 encodes a multi-domain transmembrane protein which is highly conserved across species. In humans, MEGF8 mutations cause a rare genetic disorder called Carpenter syndrome, which is frequently associated with abnormal left-right patterning, cardiac defects and learning disabilities. MEGF8 is also associated with psychiatric disorders. Despite its clinical relevance MEGF8 remains poorly characterized, and though it is highly conserved, studies on animal models of Megf8 are also very limited. The presence of intellectual disabilities in Carpenter syndrome patients and association of MEGF8 with psychiatric disorders indicate that mutations in MEGF8 cause underlying defects in synaptic structure and functions. In this study, we investigated the role of Drosophila dMegf8 in glutamatergic synapses of the larval neuromuscular junctions (NMJ) in both males and females. We show that dMegf8 localizes to NMJ synapses ...