Sister

“Just let me finish, please? They’re not using a virus as a vector. That’s the brilliant thing about it. Someone’s managed to make an artificial chromosome to get the gene into the baby’s cells. So there’s no risk to the baby. It’s incredible, isn’t it?”

It was incredible. But it didn’t stop me from worrying. I remember the rest of our phone call. I was wearing my full older-sister uniform.

“Okay, so there won’t be a problem with the vector. But what about the modified gene itself? What if it doesn’t just cure the CF but does something else that hasn’t been predicted?”

“Could you please stop worrying?”

“It might have some appalling side effect. It might mess up something else in the body that isn’t even known about.”

“Bee—”

“Okay, so it might seem like a small risk—”

You interrupted, elbowing me off my soapbox. “Without this therapy, he has cystic fibrosis. A big fat one-hundred-percent definite on that. So a small risk is something I have to take.”

“You said they’re going to inject it into your tummy?”

I could hear the smile in your voice. “How else will it get into the baby?”

“So this gene therapy could well affect you too.”

You sighed. It was your “please get off my back” sigh, the sigh of a younger sister to an older one.

“I’m your sister. I have a right to be concerned about you.”

“And I’m my baby’s mother.”

Your response took me aback.

“I’ll write to you, Bee.”

You hung up.

“Did she often write to you?” asks Mr. Wright.

I wonder if he’s interested or if there’s a point to the question.

“Yes. Usually when she knew I’d disapprove of something. Sometimes when she just needed to sort out her thoughts and wanted me as a silent sounding board.”

I’m not sure if you know this, but I’ve always enjoyed your one-way conversations. Although they often exasperate me, it’s liberating to be freed from my role as critic.

“The police gave me a copy of her letter,” says Mr. Wright.

I’m sorry. I had to hand all your letters to the police.

He smiles. “The human angels letter.”

I’m glad that he’s highlighted what mattered to you, not what’s important for his investigation. And I don’t need the letter to remember that part of it:

“All these people—people I don’t know, didn’t even know about—have been working hour after hour, day after day for years and years to find a cure. To start with, the research was funded by charitable donations. There really are angels, human angels in white lab coats and tweed skirts, organizing fun runs and bake sales and shaking buckets so that one day someone they’ve never even met has her baby cured.”

“Was it her letter that allayed your fears about the therapy?” asks Mr. Wright.

“No. The day before I got it, the gene therapy trial hit the U.S. press. Chrom-Med’s genetic cure for cystic fibrosis was all over the papers and wall to wall on TV. But there were just endless pictures of cured babies and very little science. Even the broadsheets used the words ‘miracle baby’ far more than ‘genetic cure.’ ”

Mr. Wright nods. “Yes. It was the same here.”