As the coda to a tragic and controversial story, Charlie Gard died late last month. He was born in England last year, healthy at birth, full-term and healthy weight, but his parents soon noticed he could not lift his head or support himself like babies his age.

He was eventually taken to a leading London children's hospital where he was diagnosed with an extremely rare inherited disease, infantile mitochondrial DNA depletion syndrome (MDDS), which causes progressive muscle weakness and brain damage. There are only a handful of similar cases in the medical literature and no proven treatments.

In October, Charlie was placed on a ventilator and his parents later requested that he be transferred to America for an experimental therapy called nucleoside, which had never been used in a patient of his severity. A crowdfunding page was created in January to finance the therapy, and it raised $1.5 million. But British doctors concluded that the experimental treatment would neither cure Charlie nor improve his quality of life.

Occasionally, if parents and medical staff disagree on treatment and the disagreement cannot be resolved, the state is asked to decide the issue. In Charlie's case, the well-publicized battle went to the British supreme court and then to the European Court of Human Rights, both of which denied the parents' efforts to take Charlie to the U.S. for treatment. He was ultimately transferred to a hospice in July where doctors withdrew his life-support, denying his parents their last wish that he spend his final hours at home.

When the state becomes involved in a dispute with parents about a child's care, both sides are supposed to represent the child's interests. In most cases, parents' wishes prevail, as it should be. The state should intervene only when clear evidence exists the parents are causing harm through acts or omissions. The rationale of the British courts in the Gard case was that the proposed therapy would not benefit Charlie, and he should be allowed to die with dignity. While both sides have their merits, I would have contended there was not enough evidence for the court to interfere with parental rights.

However, there is another angle to the case that went virtually unmentioned – the role of advancing medical science in extremely rare cases. The doctors offering the experimental nucleoside therapy did not guarantee, or even suggest, it would cure Charlie. No one knew whether it would cure him, improve his symptoms, have no effect, or possibly even cause his death sooner. There was simply no precedent. But any of these outcomes would provide valuable information about future cases of MDDS. In the case of such a rare disease, where there is no precedent with human subjects and there is informed consent from the patient (or in this case the parents), the imperative should be for treatment. There is simply no other way to obtain clinical information that might help future cases.

In a sense, no matter the outcome of his treatment, Charlie Gard would be doing a service to future patients by exercising what is increasingly referred to as "the right to try."

Is it unseemly to treat Charlie Gard as something of a "guinea pig" for future patients? That argument is understandable, but the very essence of medical research is that the care of a single patient today can provide benefit for many patients tomorrow. Any physician worth his or her salt would admit that, consciously or unconsciously, he or she uses knowledge or surgical techniques learned on current patients to guide the care of patients down the line. That is the nature of clinical experience, and without it medical progress is severely restricted.

There are obviously limits to thinking of patients as vehicles for gaining medical knowledge. And there are ethical norms in medicine that guide us here. It should never be done if the proposed treatment is generally recognized to be useless or injurious, or if it involves consciously causing harm to a patient, or if it is done without the patient's consent. Likewise, if the cost of treatment is prohibitive, it is unethical to pursue a longshot.

Most importantly, a completely unproven treatment like the one in this case should not be performed on a human patient if reasonable medical studies can substitute for individual observation. This is why case reports, i.e. individual observations, of common medical conditions are of little value in the medical literature. With common conditions, there are sufficient numbers of patients that other types of observational studies, including trials where patients are randomly assigned treatment or not, that provide much greater information about benefit and harm.

In the case of Charlie Gard, none of these prohibitions apply. His disease was so rare that few clinicians alive today will ever see another case, and that's why there aren't and cannot be any human studies of MDDS. And so there are no other ways of telling whether the proposed treatment might be effective, ineffective, or even harmful. Historically, with rare conditions and diseases, the drugs and surgeries that ultimately proved useful began with a longshot treatment given to a single patient.

To be sure, Charlie Gard's parents were gambling with the money they raised for his treatment. The whole judicial episode demonstrated they considered the gamble worth taking. With their son no longer alive, it is likely that if asked today, they would still say (perhaps even more strongly) that they feel the gamble was worth taking. In retrospect, for their sake and the sake of medical progress, they should have been permitted to take that risk.

Cory Franklin is a retired intensive care physician and author of "Cook County ICU: 30 Years of Unforgettable Patients."

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