Hundreds of people have joined donor registers after an appeal by Italian parents desperate to find a bone marrow match for their 18-month-old son.
Alessandro Montresor has a rare immune disorder said to affect just 0.002% of children and can only be cured with a transplant in the next five weeks.
His parents Paolo and Cristina, who met and live in London, have been “amazed” by “a tsunami of solidarity”.
An Italian donor registry told the BBC on Thursday it had a “possible” match.
A frozen stem cell sample from a woman’s umbilical cord was identified through a voluntary blood bank, the head of the Italian Bone Marrow Donor Registry (IBMDR) said.
However, Nicoletta Sacchi said that because the London doctors treating the toddler, also known as Alex, were looking for an adult donor, it was not clear whether the umbilical cord sample would be deemed good enough.
In a heartfelt Facebook message, Alex’s parents shared how their only child suffers from Hemophagocytic Lymphohistiocytsis, also known as HLH, and is currently in a clinical trial at Great Ormond Street Hospital.
The experimental drug he is receiving, his parents were told, may become ineffective after five weeks.
In response, events have been organised across Italy to get healthy people aged 18 to 36 to undergo “simple” HLA (human leukocyte antigen) testing, local media said.
Giuseppe Saponara, who ran a donor drive in Milan on Sunday, told the BBC: “This disease is very rare and the baby has an extremely rare antigen, so it is difficult to find a [match].” He said the odds were one in 100,000.
“Fifty percent of the children affected by HLH die within ONE MONTH,” the parents wrote on Facebook, “while approximately one third will develop irreversible deficiency of their neurological system.”
Alex was one case but there were many people in the world who also needed help, family friends told the BBC, urging people to become donors regardless.
“Nowadays the bone marrow donation is very simple, and does not require a theatre procedure anymore,” Alex’s parents told online supporters.
“Get in contact with your local hospital and everything is done through a limited blood sample, or a saliva sample if you are afraid of the needle.”
Alex is currently at home in London with his parents, who are trying to keep life peaceful and normal, the family friends said.