The parents of a six-month-old baby boy with leukemia have warned of the one sign they noticed that was actually a symptom of serious illness.

Little Harri Stickler, from Aberdare in South Wales, was a "happy" and "bouncing" baby boy - until his mum took him to the GP about swelling over his eye.

Less than 24 hours later, the family were rushed to hospital where their little boy was diagnosed with acute lymphoblastic leukemia.

Six-month-old Harri Stickler

Now his family are sharing their story to warn parents across the UK about the warning sign - and to desperately ask people to join the bone marrow register and give Harri the best chance.

Speaking to Wales Online, Harri's great-aunt Clare Werrett said the family are still coming to terms with the heartbreaking news, which came just weeks before Christmas.

Baby Harri was taken to the GP by his mum who spotted swelling just above his eye

Clare, 47, said: "Harri had some sort of lump or swelling by his eye. When Bethan took him to the surgery in Aberdare he wasn't himself that day but he hadn't been unwell.


Little Harri with his older brother Logan

Harri, who turned six months old while in hospital, has now begun a three-month cycle of chemotherapy to tackle the cancer, which affects the white blood cells.

If the treatment is successful, Harri will then need a bone marrow transplant to allow him to fight the disease.

Clare told Wales Online: "He's got quite a battle on his hands.

"Hopefully Harri will receive three months [of treatment], at which time they will have to do a bone marrow transplant so that's why we are determined to raise awareness and ask people to join the register.

"Unfortunately chemotherapy won't be enough so he needs that transplant."

How to join the bone marrow register

If you're aged between 16 and 40 years old there are a number of bone marrow registers you can join.

You only need to join one UK registry and they will anonymously share your information to find a match.

If you're aged between 16 and 30 and in good health you can join the Anthony Nolan bone marrow register.

Once you're on the list, you will stay there until you reach 60.

To join the register contact the charity and they will send you a swab pack in the post for to complete and send back.

Then, if you're a match, they will get in touch asking you to donate if you're still healthy and able to.

If you are aged over 30 there are other options you can take.

Those aged between 17 and 40 years old can join the British Bone Marrow Registry by telling staff when you give blood.

Harri's family are desperately appealing for people to join the bone marrow register, so they can help others in the same situation.

Clare said: "The family want to be able to do something to raise awareness of Harri and others like him who are in need of bone marrow. The more people that get on the register, the greater chance there is for Harri and others."

You can see Harri's campaign page here.