BDNF (Brain-Derived Neurotrophic Factor)

**What it means:** BDNF is a protein that acts like **fertilizer for neurons** — it promotes neuronal survival, growth, and synaptic plasticity. Without enough BDNF, neurons are fragile and connections between them don't form properly. **In MHS:** MEF2C regulates BDNF expression, so MEF2C deficiency means reduced BDNF, which compounds the neurological damage. It's like trying to build a house while simultaneously cutting the supply of building materials.