Retinal (eye) in the context of gene therapy

**What it means:** The retina (the light-sensitive layer at the back of the eye) was actually the **first tissue** where gene therapy succeeded (Luxturna, 2017). The eye is "immune-privileged" — meaning it doesn't trigger as strong an immune response as other tissues, making it easier to deliver gene therapy there. **Why this matters for MHS:** If gene therapy works for the eye (which is hard), it gives confidence that brain gene therapy is possible too. But the brain is arguably even harder than the eye — you need not just delivery but also targeting the right cell types (neurons AND microglia) throughout the entire brain.