Eligibility and assessment

Gene therapy is not offered to everyone with sickle cell disease or beta thalassaemia. There are written criteria, and then there is an assessment that only a specialist centre can carry out.

This page sets out what the criteria say. It cannot tell you whether you meet them, some of the criteria involve clinical judgement, and only a specialist team can make that call.

The written criteria

Severe sickle cell disease

NICE recommends the treatment, through managed access, for people aged 12 and over who:

• have had at least two vaso-occlusive crises a year during the previous two years, and

• have one of three genotypes, βS/βS, βS/β⁺ or βS/β⁰, and

• are people for whom a stem cell transplant would be suitable, but who do not have a matched related donor available.

Transfusion-dependent beta thalassaemia

NICE recommends the treatment, through managed access, for people aged 12 and over for whom a stem cell transplant would be suitable but who do not have a matched related donor available.

In both cases the treatment is funded on the condition that the managed access agreement is followed, which means data is collected while people are treated.

The two criteria people misread

Two of these are worth spelling out, because they surprise people.

"A transplant would be suitable, but no matched related donor is available", this is not a technicality. If you do have a matched donor in the family, a transplant is normally the conversation first, and gene therapy is written for people who do not have that option.

"Aged 12 and over", this is the UK licence. You may read that regulators elsewhere have approved it for younger children. That is true in the United States; it is not the position in the UK, and a UK team cannot work to another country's licence.

There is also an upper age limit, and it is not in the guidance

Neither the licence nor NICE sets a maximum age. But the referral form that English clinicians actually have to complete does.

The National Haemoglobinopathy Panel's gene therapy referral form, dated July 2026, states that gene therapy "is only being considered in age 12-40", and between 40 and 45 only "in very exceptional circumstances" with additional scrutiny.

This is a decision about how the service is being run rather than a rule about the medicine, and the form dates it to 2026, which suggests it is reviewed. But if you are over 40 it is the fact that will most affect you, and you would not find it by reading NICE or the product licence.

How a referral actually happens

You cannot refer yourself. The route runs through your own team and then through a national panel.

1. Your red cell consultant raises your case at your local haemoglobinopathy team meeting.

2. If there is agreement, they refer you to the National Haemoglobinopathy Panel.

3. The panel discusses and approves cases at a monthly meeting.

4. Where suitability is unclear, for example if organ function is borderline, the case goes on to a national transplant group.

Panel approval is not a formality or a clinical courtesy: it is written into the funding agreements for both conditions. Without it the treatment is not funded.

The practical consequence is that the first conversation is with your own haematology team, and everything else follows from that.

What the assessment involves

Being eligible on paper is the beginning. A specialist centre then assesses whether treatment is safe and sensible for you specifically, because conditioning chemotherapy is demanding and how well your organs are working matters.

We have not published a checklist of the tests involved, because no NHS or regulator source sets one out for this treatment specifically, and inventing a plausible list would be worse than saying so. Your centre can tell you exactly what they will assess and why.

What is clear is that fertility should be discussed as part of this stage, not after it.

Where it is done

Treatment is delivered at a small number of specialist centres, not at every hospital.

• For thalassaemia, NHS England said the therapy would be offered at seven highly specialist centres, with around 460 people in England potentially eligible.

• For sickle cell, it named centres in London, Manchester and Birmingham, and expected around 50 people a year to be treated, out of roughly 15,000 people in England living with the condition.

Those two announcements describe different services and we have not found a single reconciled list of centres, so ask your team which centre you would be referred to and how far it is.

How many people are actually being treated

This is worth knowing before you set expectations, and the numbers are not the ones in the headlines.

For sickle cell, NICE's own planning figures estimate around 1,800 people in England are eligible. It projected that 29 people would start treatment in 2025/26 and 23 would complete it, rising to about 96 starting and 78 completing a year by the end of the decade.

So being eligible and being treated soon are very different things. Fewer than one in fifty eligible people were expected to be treated in the first year. Capacity is limited and manufacturing takes months. If you are told there is a wait, that is the shape of the programme rather than something going wrong with your case.

These arrangements are for England. Scotland, Wales and Northern Ireland decide separately and are not covered here.

Questions you might take to your team

• Do I meet the criteria, and if not, which part?

• Have I been tested for a matched related donor?

• Which centre would I go to, and how far would I travel?

• What does the assessment involve, and how long does it take?

• What would stop me being eligible later, could that change?

• Where does the fertility conversation fit in this stage?