Francis, from Walton, Liverpool, was just six weeks old when his mother Anna spotted an unexplained bruise on his arm.

Initial blood tests failed to reveal anything abnormal.

But Francis, described by Anna as a "joyful" baby who "hardly ever cried", was eventually given a bone marrow biopsy when he became very ill and tired.

He was diagnosed with acute myeloid leukaemia (AML), a type of blood cancer that causes the bone marrow to make too many abnormal white blood cells and prevents it from making healthy blood cells.

The biopsy showed his bone marrow was 80% cancer cells.

The risk of developing AML increases with age and is most common in those over the age of 75.

About 3,100 people are diagnosed with AML in the UK each year, according to the NHS.

Francis has been admitted to Alder Hey Children's Hospital in Liverpool where he will undergo chemotherapy before being transferred to Manchester Children's Hospital in November.

"Finding out that our baby has blood cancer has completely turned our world upside down," Anna said.

"You never think something like this will happen to you, you feel so desperate.

"We're devastated that Francis is having to face something so hard so young."

Doctors have told the family that Francis will need a stem cell transplant at the end of his treatment - his only chance of a cure.

The family is now urging people to join the Anthony Nolan stem cell register to find Francis a match.

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"If you're able to sign up, please consider becoming a stem cell donor," Anna said.

"You could save the life of someone like Francis and give hope to their loved ones too."

Anthony Nolan will send those who sign up a cheek swab, which should be returned to the charity before a person is added to the register.

Henny Braund, chief executive of Anthony Nolan, said: "It would mean everything to Francis's family to find him a donor before November when he will need his transplant.

"We will be supporting them as they wait for news of a donor who could give him a second chance at life.

"If you're aged 16-30, in good health, you could give hope to someone like Francis by joining the Anthony Nolan register today.

"We are particularly urging young men to consider signing up - they are far more likely to be chosen to donate but are less likely to sign up."