Primary creatine disorders highlight a role of creatine in brain physiology.
SLC6A8 takes part in creatine transport and re-uptake but also in biosynthesis.
Secondary creatine defects stress dependence of creatine metabolism on many pathways.
The high dependence on multiple metabolic pathways supports creatine as a cell sensor.
Creatine is a potential sensor of cell methylation and energy status.