The American doctor behind an experimental treatment in the USA is to examine Charlie Gard on Monday and Tuesday.
The 11-month-old boy suffers from mitochondrial depletion syndrome, a rare genetic disease that has left him brain-damaged and unable to breathe unaided.
Specialists at Great Ormond Street say that the therapy is experimental and will not help Charlie.
Hirano was invited to make the visit after offering an experimental gene therapy he believes has a 10% chance of improving muscle strength and bringing a "small but significant" improvement to Charlie's brain function.
Baby Charlie Gard, the 11-month-old with a rare, terminal medical condition who has been the center of an ongoing legal battle, will be evaluated by a doctor from the United States.
The mother, Connie Yates, told the Press Association that doctors at Great Ormond Street wanted to turn off Charlie's life-support but decided not to after the White House intervened.
Hirano's research focuses on mitochondrial diseases and genetic myopathies and he has treated others with conditions similar to Charlie's.
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Great Ormond Street had said Charlie's mechanical ventilator would be switched off after the European judgment, but the hospital has since given the boy's parents more time to spend with him before this happens.
Mr Justice Francis has considered the couple's latest claims at preliminary hearings in the Family Division of the High Court in London over the last few days.
Ms Yates and Charlie's father, Chris Gard, want Mr Justice Francis to rule that Charlie, who suffers from a rare genetic condition and has brain damage, should be allowed to undergo a therapy trial overseen by Dr Hirano in NY.
But judges in several courts - most recently the European Court of Human Rights - told his parents that taking Charlie overseas was not in his best interests.
He will meet with doctors and medical experts at the hospital to discuss his treatment.
Every ruling has been in favor of Charlie's specialists at Great Ormond Street Hospital.