The price of new drugs to treat rare genetic disorders, frequently called “orphan” diseases, has been debated periodically for four decades. And the recurring question has been, “Can we afford these treatments?”

In the 1970s, the discussion focused on the cost of treating boys with hemophilia, as it was sometimes more than $300,000 a year if the child required high doses of drugs. In the 1980s, it centered on bone marrow transplants, which today cost about $200,000, and in the 1990s and 2000s, it focused on enzyme replacement for disorders like Gaucher disease and Fabry disease (about $250,000 a year). Some of the drugs emerging now, and some that are likely to come soon from gene therapy and gene editing, may cost as much as $1 million per patient or more.

There are three principal reasons they’ll be so expensive: the drugs require hundreds of millions of dollars to develop, the diseases they target are very rare, and a single treatment might be sufficient to stabilize or reverse the disease — an intervention unlike anything in the history of the pharmaceutical industry.

It is commercially challenging to develop drugs for a very small number of patients. Nevertheless, scores of companies, ranging from the giants in the pharmaceutical industry to tiny venture capital-backed biotech startups, are targeting disorders that affect only a few hundred patients in the United States. When we have so many other pressing health care problems to confront, why has the orphan drug initiative grown so fast? And why does it make sense, both clinically and socially, for our society to pay for the rising number of expensive therapies?

The Orphan Drug Act

The 1983 Orphan Drug Act provided special tax incentives and market benefits to companies that successfully developed new drugs for diseases that afflict fewer than 200,000 Americans (about 1 in 1500). Although the law was in part written with genetic disorders in mind, most drugs awarded “orphan” status have been created for cancers. The sequencing of the human genome and the associated expansion of new technologies to study disease at a molecular level now allow us to identify the core problems in hundreds of single-gene disorders, and find a pathway to treatment. The prospects for success are often considerably better than in complex diseases like asthma, heart failure, and Alzheimer’s. Preclinical development may proceed faster, safety may be less of a concern (because orphan drugs may have fewer side effects), expensive clinical trials will be smaller in scale, and affected families may become powerful allies.

Patient foundations, often founded by families, are single-minded in their pursuit of treatment for rare, devastating genetic disorders. They create patient registries, conduct natural history studies, engage with leading scientists as intellectual equals, fund young investigators, and critically review research. In some cases, they exceed the National Institutes of Health in annual allocation of research dollars for specific disorders.

A fine example of a foundation-pharmaceutical partnership is that between the Cystic Fibrosis Foundation and Vertex Pharmaceuticals; in 2012, it led to the approval of the first drug to treat the molecular problem caused by a mutation in the cystic fibrosis gene.

What If We Didn’t?

It is natural to cringe at the charges for such treatments and tempting to decry the industry for price gouging, but first, let us ask another question: What is the cost of not developing such drugs?

Children and adults with sickle cell anemia often live in chronic pain from multiple small strokes, require frequent hospitalizations, and over several decades become severely incapacitated. Children born with beta-thalassemia often need monthly blood transfusions and suffer from iron overload (which can cause serious damage to the heart). Children born with phenylketonuria (PKU) must immediately be put on a special diet and stay on it for life, or else develop severe neurological problems. The diet is expensive (about $10,000/year) but tens of thousands of people with PKU follow the diet and lead normal lives. In mid-childhood, most children with X-linked adrenoleukodystrophy (ALD) either undergo bone marrow transplant (if the tricky diagnosis is made in time) or slowly decline over several years to a vegetative state, before they die. It can cost more than $1 million to provide supportive care for children who are diagnosed too late for a transplant to help. But if performed early enough, bone marrow transplants (and, someday, gene therapy) may arrest the disease and normalize the child’s life. There are several other examples.

For many of the hundreds of severe single-gene disorders, the cost of “supportive care” — usually our only option — is extremely expensive, but this care does not end in either disease stabilization or a cure. Of course, the cost to a family of watching a child suffer for years before dying is incalculable. Surely, we all agree that none of us wants to stand in the shoes of these families.

We are well into a new era of drug development that will greatly improve the prospects for cures for many non-genetic diseases. Nowhere is this more evident than in the new treatments for patients with hepatitis C, for which a therapy given over several months at a cost of $60,000 to $80,000 cures patients who may otherwise be headed for liver failure or liver cancer (for which treatment is far more expensive). The field of cancer care is in a golden age, with many new therapies (often keyed to a “driver” mutation in the tumor’s DNA) entering the market at a cost of about $100,000 per patient and extending life by a few months to a few years. These treatments are mostly used by older people. Spending $1 million to restore a full life to a young child may well generate a better return on investment to society than spending one-tenth of that on an elderly cancer patient. We are all at risk for cancer, and we are all at risk for having a family member diagnosed with a rare genetic disease.

Right now much of the debate over paying for costly breakthrough drugs is being played out in state Medicaid programs, for which the federal government provides about half of the funding. Thus, a big chunk of the costs of paying for these drugs are born by us — the taxpayers.

In 1968, the great biologist, Garrett Hardin, wrote a highly influential essay warning about the “tragedy of the commons,” arguing that actions based solely on self-interest could doom us all. The original notion of the “commons” addressed overuse of shared pastureland. (Today, a prime example is the threat of global warming, which we will contain only if we act in common.) I would argue that no commons is more important than our “genetic commons,” that is, our children — all of them. No parent should have to worry that new drugs to save children with rare disorders are beyond financial reach. If shown to be effective, new therapies for orphan genetic disorders may confer 70 years of normal life to a child. It does not take fancy financial analysis to argue that $1 million spent to cure an extremely debilitating disease in a child is money well spent.

Philip R. Reilly, MD, JD, is a venture partner at Third Rock Ventures in Boston, Massachusetts. Trained in internal medicine and clinical genetics, he specializes in starting and growing  companies that develop breakthrough therapies for orphan genetic diseases. Dr. Reilly has served as president of the American Society of Law, Medicine, and Ethics; was executive director of the Eunice Kennedy Shriver Center for Mental Retardation; and was on the faculty at Harvard Medical School and Brandeis University, among other positions. His book Orphan: The Quest to Save Children with Rare Genetic Disorders was recently published.