Columbia University medical school specialist Michio Hurano on Monday examined Charlie Gard with British colleagues ahead of a High Court hearing on new experimental treatment and a possible move to the USA for the terminally ill 11-month-old British boy, whose Great Ormond Street doctors are poised to pull the plug after earlier British and European court rulings.
He further noted that the small number of people with Charlie's rare genetic condition, mitochondrial DNA depletion syndrome, would make robust clinical trials hard.
Charlie's parents are fighting for the right to take the 11-month-old to the USA for a therapy trial for his rare genetic condition, overseen by Dr Hirano.
But Britain's courts have refused permission on the grounds it would prolong his suffering without a realistic prospect of it helping the 11-month-old child. Hirano has offered to treat him with an experimental gene therapy he believes has a 10%...
Charlie's parents, Connie Yates and Chris Gard, have been trying to send their son to the United States to undergo Hirano's therapy.
Doctors at Great Ormond Street argue life support should be withdrawn, saying that Charlie's condition - a form of mitochondrial disease which causes progressive muscle weakness and brain damage - would affect his quality of life.
"It may be unconventional but this case is full of unconventional aspects", the judge said.
But last week, the case returned to the High Court after the hospital asked for a new hearing to consider new evidence from Hirano.
Hirano says the therapy he is developing could improve the condition of Charlie who suffers from a form of mitochondrial disease.
Every ruling has been in favor of Charlie's specialists at Great Ormond Street Hospital.
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.