TBC1 domain-containing kinase (TBCK) is a pivotal protein essential to brain development, with a complex structure comprising a Protein Kinase domain, a Tre-2 Bub-2 Cdc16 (TBC) domain, and a Rhodanese domain. Mutations in this protein are known to cause TBCK Syndrome, a rare genetic disorder characterized by a spectrum of neurological and developmental abnormalities. In patients, these mutations disrupt cellular pathways, leading to impaired brain development and functioning, which manifest in the diverse and often severe clinical symptoms observed in affected individuals. To further understand how TBCK mutations could affect brain development and behavior, we developed a knockout (KO) mouse model for TBCK. However, our team faced several challenges related to the viability of the mice. Consequently, because there was also a visible phenotype in heterozygous animals, we decided to perform a series of assays to determine if mutations in one allele of TBCK would be sufficient to affect the development and behavior of the animals. Our findings suggest that TBCK haploinsufficiency leads to a subtle but significant neurological phenotype, with observable differences in behavior and mTORC1 signaling pathway in Tbck+/– mice. We extended our study to a human Phenome-Wide Association Study (PheWAS), identifying associations between TBCK heterozygote status and specific neurological manifestations. Notably foot and toe deformities were associated with TBCK mutations. To better understand the impact of these mutations in an unbiased way, we employed the power of multi-omics to dissect different levels of regulation affected in patients.Our comprehensive analysis using RNA sequencing, proteomics, and miRNA sequencing in patient-derived fibroblasts revealed significant alterations in ribosomal function, RNA splicing, and miRNA expression. This holistic view of the cellular landscape in TBCK syndrome uncovers potential therapeutic targets and provides a richer understanding of the disease's complexity. This thesis work offers novel insights into TBCK syndrome, highlighting the nuanced effects of the mutations and laying a foundation for future research into targeted therapies.