Credit: Ron Tom/ ABC

On the most recent episode of Grey’s Anatomy, the ER was full of burn victims, Callie gave a TED talk, and we found out Meredith and Derek’s baby is a boy – yay! But most importantly, Meredith has finally agreed to find out if she carries the gene for Alzheimer’s. But what will happen this week? This promo for Season 9, Episode 20: “She’s Killing Me,” gives us a few clues about what might be in store for the Grey’s gang on Thursday.

There’s a mysterious outbreak at the hospital. Of what? We’re not sure, but it seems serious, especially since Mr. Intense Voiceover Guy says it’s deadly. Could it possibly be a new medical mystery only our favorite doctors are capable of solving? We hope so!

This disease shakes the whole hospital…. and someone makes a mistake that really pisses Bailey off. It appears a patient is lost in the process of treating the outbreak, and according to Owen, it’s a nightmare. Could someone’s job be in jeopardy? This mistake might be a game changer for the dynamic of the rest of the season.

Meredith’s genome mapping results are in. Seems like Bailey tells her the results are positive… but are they really? It doesn’t make much sense that they would reveal something so important in a promo. Most likely, it’s just misleading us – and with Grey’s, there’s always a twist.

For more Grey’s spoilers, click here.

Catch the next new episode of Grey’s Anatomy on Thursday, April 4, 2013, at 9 p.m. ET/PT on ABC.

Credit: YouTube Photo: Grey's Anatomy Season 9, Episode 20 Preview: Does Meredith Have Alzheimer's?