Generally, the diseases are treated via blood transfusions from donors, but they come with complications.

Up to 17% of patients are susceptible to side-effects after a transfusion, including pain, stroke, and acute pulmonary deterioration, because the donor's blood doesn't accurately enough correspond with theirs.

The breakthrough test by NHS England and NHS Blood and Transplant (NHSBT) will involve blood group genotyping - a detailed DNA analysis of each patient's blood group - which will be used to more accurately match those in need of transfusions to donated blood.

As a result, reactions to donor blood - where antibodies attack donor blood cells - are reduced and patients are more certain they are receiving the best treatment.

NHS England will provide funding of nearly £1m to NHSBT to provide blood group genotyping in its specialised molecular diagnostics laboratory. A donor database will then be developed.

Currently, blood donors tend to be those from a European ancestry, however a large group of sickle cell disease patients are of African and Caribbean backgrounds, while thalassemia sufferers are usually of Asian and Southern Mediterranean heritage.

About 17,000 people in England suffer from sickle cell disease, where red blood cells become sticky, block vessels and restrict oxygen supply causing intense pain. There are around 250 new sickle cell cases every year.

Meanwhile, there are about 800 thalassemia patients in England with less than 50 new cases each year.

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Thalassemia patients produce either no or too little haemoglobin - which is used by red blood cells to carry oxygen around the body - and this can cause chronic tiredness.

Health Minister Neil O'Brien said: "This £1m investment in genotyping is a potential game changer in tackling the painful side effects many sickle cell disease and thalassemia sufferers experience following a blood transfusion. It could also be used to stop the progression of the diseases in their tracks.

"Matching blood more accurately is vital for sickle cell and thalassemia patients - we urgently need more blood donors from these communities to come forward as they are more likely to have the necessary blood type vital to treat these disorders."

'They give my body a future chance of survival'

Stephanie Danso has sickle cell and receives a red cell exchange every six to eight weeks.

Ms Danso, 30, who is part of the complex patient group because it is difficult to find blood which she can safely receive, has previously developed blood group antibodies from transfusions which left her in intensive care.

Genetically testing her blood should, in the future, help her receive the best matched blood, reducing the risk of producing even more antibodies.

She said: "A lot of people think you only need a blood transfusion during a crisis, however for me they don't just save my life, they also give my body a future chance of survival.

"There are still days when I feel exhausted and face challenges but thanks to the transfusions I lead a happy life with lots of friends and I am working as a professional.

"I know it's difficult to find well matched blood for me now. I have antibodies from past transfusions. The new blood group genotyping will mean I can receive the best matched blood in the future with less chance of developing more antibodies and less chance of not being able to receive blood at all."