Alternately, officials said they would be willing to ship an experimental drug to the Great Ormond Street Hospital in London, where the baby is now being treated, if the Food and Drug Administration approves.

American physicians would “advise their medical staff on administering it if they are willing to do so,” the statement said.

Charlie Gard was diagnosed with an extremely rare form of a disease called mitochondrial DNA depletion syndrome, believed to affect just over a dozen children worldwide. The syndrome prevents cells from producing the energy needed to sustain organs.

The baby was brought to the London hospital on Oct. 11, when his parents, Connie Yates and Chris Gard, both in their 30s, noticed he was not growing and could not lift his head. He has been there since, breathing with the help of a ventilator and fed through a tube.

He is deaf and suffers from persistent seizures, and appears to have suffered brain damage.

Researchers at Columbia University have provided an experimental treatment to a child in Baltimore, Art Estopinan Jr., suffering from a similar but less severe form of the syndrome.