Homocystinuria Mechanism

One blocked enzyme, two roads, and the lab pattern that tells you which one is closed. This works the pathway on the board — methionine to SAM to SAH to homocysteine, and then the two things the body can do with homocysteine once it's there. When CBS is blocked, homocysteine piles up and methionine climbs with it, which is why a high homocysteine alone doesn't tell you anything and the methionine does. Also covers how homocysteine damages fibrillin at the disulfide bonds, and why cysteine becomes an essential amino acid in these patients. For the brain that needs it different.