The Letter That Wrote Itself

The diagram was taped crooked to the corridor wall, and Maya was reading it upside down before she bothered to tilt her head.

"That's blood," she said. "That round one. That's a red blood cell."

"And that one next to it is bent," said Soren. He leaned in. Someone had drawn two cells side by side. One was a soft circle, like a doughnut with the hole not quite punched through. The other was a thin curved sliver, sharp at both ends.

"That's the sickle," Maya said. "That's what Priya has. Her cells fold into that shape and get stuck in the little tubes. That's why she hurts."

Behind the door, a machine beeped in a slow patient rhythm. Priya was in there. She was fourteen and she had been in and out of this hospital her whole life, and today she had come back from somewhere in a wheelchair looking tired and strange and happy all at once.

"So what did they do to her," Soren said. It wasn't quite a question. He was looking at the third picture on the diagram, which was a bag. A bag of blood, hanging from a pole, with an arrow pointing back into a drawing of a person.

"They gave her blood back," Maya said.

"Whose blood?"

Maya stopped. That was the thing she hadn't fit yet. She kept the not-fitting things in a line in her head, and this one moved to the front.

"The arrow goes out of her and back into her," she said slowly. "Look. Out. Then this box. Then back in. Same person. It's her own blood."

"Then it wouldn't help," Soren said. "If it's her own cells they'd still be bent. You can't give someone the broken thing back and fix them."

"Unless," Maya said, and then she didn't finish, because she was looking at the middle box. The box between out and back in. It had tiny letters printed inside it. She read them out. "C. R. I. S. P. R."

"Crisper," said Soren.

"It's not a word."

A nurse went past with a cart. She slowed, saw them reading the wall, and half smiled.

"You two related to the patient?"

"She's my cousin," Maya said. "What happens in the middle box?"

The nurse glanced at the door, at her cart, at the clock. "They take out the cells that make her blood. The stem cells, from the marrow. They fix them in the lab. Then they put them back." She was already moving. "You'd have to ask the doctors the rest. It's above my pay grade, honestly." And she was gone down the corridor, cart wheels ticking.

"Fix them how," Soren said, to nobody, because that was the only part that mattered and the answer had walked away.

Maya pointed at the two cells again. The round one and the bent one. "The shape comes from something inside," she said. "Priya told me once. She said her body reads a set of instructions and it reads one letter wrong. And because of the one wrong letter, the cell folds up crooked."

"One letter," Soren repeated.

"That's what she said. Like a whole book that's fine except one letter is a typo, and the typo bends everything."

Soren took out his notebook. He wrote the two cell shapes, the round and the sliver. Then between them he drew a small box, and in the box he wrote a single letter, and then he crossed it out and wrote a different one above it.

He looked at what his hand had done for a while.

"They don't give her new blood," he said. "They don't give her someone else's cells. They take her own cells out, and in the box they go into the letter, the actual letter, and they change it."

"You can't change a letter inside a cell," Maya said. But she said it the way you say something to hear if it's still true. It didn't sound true anymore.

"CRISPR," Soren said. "That's the box. That's the thing that changes the letter." He pressed the pen down. "It goes in and finds the one wrong spot in the whole book and fixes just that spot. And then they grow the fixed cells and give her back her own blood. Except now it's spelled right."

Maya sat down on the floor against the wall. She did that when a thing got too big to stand up next to.

"So the blood in that bag," she said. "It's Priya. It's still all Priya. Every cell. But somebody went in and found one letter, in a body, in a person, and changed it. On purpose. And it worked."

"We don't know it worked yet."

"She was smiling like it worked."

They were both quiet. The machine beeped its slow rhythm through the door.

"There are billions of letters in there," Soren said. His voice had gone careful. "In every cell. And the difference between hurting your whole life and not hurting is one of them. One. And it was hidden in all the billions and somebody found it."

Maya looked at her own hand. She turned it over. Under the skin of her wrist there were the faint blue lines of her own blood, going somewhere, coming back.

"It's in me too," she said. "The book. The whole thing. Written down in every single cell I have. I've been carrying the instructions for me around the whole time and I never read a word of it."

"Nobody's read most of it," Soren said. "There's way more we can't read yet than we can."

"But we found this letter." Maya stood up. She wasn't tired next to it anymore. "We found one. In the whole book. And we changed it and it fixed her."

The door opened. Priya was in the doorway in the wheelchair, pale and grinning, and she saw the two of them standing at her diagram on the wall.

"You found my typo," she said.

Maya reached out and touched the crooked corner of the taped diagram, and pressed it flat against the wall so it hung straight.