TRAPPC9 (trafficking protein particle complex subunit 9) is a multifunctional protein with roles in both cellular trafficking and immune signaling. As a component of the TRAPP-II complex, TRAPPC9 mediates vesicle tethering and transport from the endoplasmic reticulum to the Golgi apparatus, as well as intra-Golgi and endosome-to-Golgi trafficking in mammalian cells 1. Beyond vesicular transport, TRAPPC9 functions as a modulator of NF-κB signaling by regulating IKK complex phosphorylation and activation 1. The protein exhibits preferential maternal allele expression (~70%) and plays critical roles in neurogenesis and neuronal differentiation 2. Biallelic loss-of-function mutations in TRAPPC9 cause autosomal recessive intellectual disability syndrome (NIBP Syndrome/MRT13), characterized by profound developmental delay, microcephaly, speech disorders, and brain atrophy 34. Recent findings extend the disease phenotype to include autism spectrum disorder, obesity, dysmorphic features, and abnormal N-glycosylation consistent with congenital disorder of glycosylation (TRAPPC9-CDG) 56. Maternal allele loss produces more severe pathology than paternal loss, reflecting the gene's imprinting 2. TRAPPC9 dysfunction impairs vesicle trafficking and lipid metabolism, contributing to neurological manifestations 7. These findings establish TRAPPC9 as essential for brain development and metabolic homeostasis.