Creatine is an essential metabolite for the storage and rapid supply of energy in muscle and nerve cells. In humans, the creatine deficiency syndrome (CDS) is manifested by impaired metabolism, transport, and distribution of creatine throughout the body leading to severe forms of mental disabilities. One of the common cause of CDS is mutations that impact the function of the creatine transporter (SLC6A8). This study characterized 30 missense variants of SLC6A8, which include 15 variants of unknown significance and two which were not reported before. These variants were expressed in HEK293 cells, and their subcellular localization and transport activity was assessed. Further, for the first time the interactome of SLC6A8 WT was characterized by quantitative interaction proteomics. Computational methods were then used to first assess the impact of mutations upon the thermodynamic stability of SLC6A8. This was expanded by modeling the impact of mutations upon the inward and outward facing transporter conformation. Next, identified SLC6A8 protein interactions binary complexes were modelled and used to characterize the impact of variants upon the thermodynamic stability of the complexes. This was followed up, by performing for a subset of the variants the interaction proteomics analysis to study changes upon the identified SLC6A8 WT interactome.