Profiles in precision medicine
Associate professor, Western Washington University
When I was younger I watched my mother’s decline, and eventual death, from Huntington’s disease. It was a terrifying experience. So naturally when my wife and I learned that I had inherited the mutation that causes the disease, we were devastated.
We both understood the odds for any children we might have. As the child of a parent with Huntington’s, you either have the mutation (and will surely develop the disease) or you don’t, in which case your family is free of it forever. Since Huntington’s is a dominant disease, meaning you need only one copy of the mutated gene to fall ill, 50% of the children of people with Huntington’s face the same fate as their sick parent.
After receiving my test results, my wife and I decided we’d never have biological children.
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Years later we heard about a new procedure called pre-implantation genetic diagnosis, whereby embryos generated for in vitro fertilization can be screened for Huntington’s. By implanting only healthy embryos, we could reduce our child’s risk of inheriting the disease from 50% to essentially zero. So we changed our minds.
Our city had an IVF clinic that had recently established a pre-implantation diagnosis program, but it hadn’t yet had a successful pregnancy as a result of genetic screening. We would be its guinea pigs.
We got lucky. In 2006 my wife gave birth to healthy twins who did not inherit the mutation. Now that more than 12 years have passed, I can say that using this technology to have healthy kids was one of the most powerful ways I’ve had to fight back against my diagnosis.
We still don’t have any disease-modifying treatments for Huntington’s, although I’m hopeful there will be in time for me. But either way, pre-implantation genetic diagnosis gives parents affected by genetic diseases a cure for their kids, and for all future generations.
Cystic Fibrosis Patient
I was born in 1977. At age two I was diagnosed with cystic fibrosis, a disease caused by a defective gene that changes a protein that regulates how cells process salt. The average life expectancy was 14 years. My parents, who had never heard of cystic fibrosis, were in panic. They devoted their lives to the Cystic Fibrosis Foundation and to date have raised more than $750,000 for drug research and development.
The disease didn’t get to me as early as my parents feared. I began working at 16, stayed employed through college, and ultimately had to stop studying only because my need for medical insurance trumped a college degree. I ended up in retail management, and by the time I was 36, I’d been a store manager for two different multimillion-dollar companies.
But the long hours and inconsistent schedule took a toll on my health. When my pulmonologist noticed a significant drop in my lung function, I had to apply for disability. I had lived my life with the philosophy: “I have CF. CF doesn’t have me.” I was wrong.
The good news was that my parents’ hard work paid off. We now have drugs that don’t only treat the symptoms of cystic fibrosis but attack the disease itself at the molecular level. These drugs, tezacaftor and ivacaftor, work together to address a missing protein, known as CFTR, caused by a genetic mutation.
The bad news is that the cost of this treatment is beyond my family’s means. The retail price of the drugs I need exceeds $38,000 a month. My husband has a private medical insurance policy provided by his employer. But because I’m on Medicare, I can’t use his insurance, since Medicare recipients are prohibited from being on private medical policies. It’s considered “double dipping.”
I know we may be close to being able to edit the CF mutation out of embryos, or select embryos without the mutation. I support these advances, since they can end the suffering and early mortality caused by CF.
But those advances won’t help me. I’ve been off the drugs I need for eight months. This landed me in the hospital on intravenous antibiotics for three weeks in August. I lost 26% of my lung function. Each day is a mental and physical battle with an unknown outcome.
Modern medicine gives us many gifts. But for many of us, those gifts are out of reach.
CEO, Color Genomics
San Francisco, California
My grandmother died from breast cancer. My mother, who survived two breast cancers, got tested and discovered that she is a BRCA2 mutation carrier, explaining our family’s history. I later got tested and discovered that I, too, was a carrier of the same mutation: 1466DelT. One typo with consequences.
I learned of this almost 15 years ago. I’m now the CEO of a major genetics company.
When my wife, Elizabeth, and I started to discuss having children, I raised the issue of my mutation. We decided that we’d do pre-implantation genetic testing: that way we could select embryos based on whether they carried the mutated gene. I wanted to ensure that our children would be free of that cancer risk.
Elizabeth was just coming off birth control, so our doctor told us it was unlikely that she would get pregnant for a while, and suggested we return for the testing in a few months. Thinking nothing of it, we went back to life as usual. Almost immediately, Elizabeth got pregnant.
At first I was distressed that we were expecting a child without knowing whether he or she carried my mutation. But I came to terms with it and put the question out of my mind—after all, there wasn’t much I could do about it.
Fast-forward a couple of years, and as we watched our first child, Kamal, take his first steps, Elizabeth said something striking: “I am so grateful for this child. This specific child. If we had gone through embryo selection, it would have been a different child, who would not have been Kamal. This child who we love and adore would not exist.”
To me, that changed everything. I believe that this is a deeply personal choice—without a cosmically right or wrong answer. However, the thought that our choice would have caused our beautiful child to not exist convinced me that—at least for my BRCA2—we were willing to let fate call the shots.
Today, we have three wonderful boys: Kamal (five), Rami (four), and Zak (one). All of them may or may not have the BRCA2 mutation, and we would have it no other way.
Paula Amato, MD
Oregon Health & Science University, Portland, Oregon
Last year, I took part in an experiment that a lot of people think was ethically questionable. I was part of a team at Oregon Health & Science University that used CRISPR gene editing to correct a disease-causing gene mutation in human embryos. In other words, we were “editing” humans.
Why would we do this? With our work we were able to correct a mutation in a gene called MYBPC3. This mutation causes a deadly heart condition known as hypertrophic cardiomyopathy. Our work was potentially a first step toward eliminating the disease from that family and all its descendants.
Some people argue that we shouldn’t pursue our research, and that instead women should simply undergo a pre-implantation genetic diagnosis, which could identify any embryos with the mutation before they’re implanted. This sentiment is most likely uttered by people who have never treated an IVF patient.
One recent patient of mine and her husband easily conceived their first baby, who unfortunately was born with a disease called spinal muscular atrophy (SMA), a rare genetic neuromuscular disorder characterized by loss of motor neurons and progressive muscle wasting. The baby passed away at age one. The mother subsequently completed two physically burdensome rounds of IVF at a cost of tens of thousands of dollars. She made a total of four embryos, only one of which was chromosomally normal and unaffected with SMA. We transferred that embryo, but unfortunately it did not take.
Such cases are not at all unusual. The type of gene editing we’re researching would complement pre-implantation diagnosis by reducing the number of cycles of IVF required. It would relieve patients of the associated physical burden and costs. And it would rescue the affected embryos.
Another patient of mine, who carried the BRCA gene mutation, which increases the risk of breast and ovarian cancer, came to see me for IVF and pre-implantation genetic testing to avoid passing on the gene to her children. She was conflicted—if her parents had made a similar choice, she wouldn’t be here today. And she was right. They would have selected a different embryo. But what if instead, she (the very same person) could have been born, just without the BRCA mutation?
That’s what our research promises. That’s why we’re doing it.
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