Gene Therapy Vector Optimisation (for AAV packaging)

**What it means:** The MEF2C gene is relatively large — about 12-13 kilobases (kb) of DNA. But the AAV vector can only carry about 4.7 kb of genetic material. So the UT Southwestern team had to "shrink" the MEF2C gene into an AAV-compatible format, typically by using: - A minimal promoter (the smallest "start" signal that still works) - Introns removed (non-coding sequences spliced out) - A compact polyadenylation signal **The challenge:** Making MEF2C fit in AAV is like trying to fit an elephant in a Mini Cooper. You can do it by removing interior trim, seats, and carpets — the core function still works, but there's very little room for error. Any mistake in the shrunken gene could reduce expression levels.