Corrective treatment of CID

Haematopoietic stem cell transplantation

In some cases, haematopoietic stem cell transplant (HSCT) (including bone marrow transplant, BMT) offers the potential for long-term cure of CID. This
treatment is most well-established for defined types of CID that are known to be life-limiting because of predictably severe complications.

HSCT aims to replace the faulty immune system with an immune system from a healthy donor. Stem cells, from which all the cells of the immune system develop, can be obtained from healthy bone marrow, or in some cases from umbilical cord blood or donor blood. The healthy stem cells can be given by transfusion into a vein to a child with CID.

HSCT is not an operation like a heart or kidney transplant. Stem cells contained
in the donor bone marrow are able to find their way from the bloodstream to
the child’s bone marrow, where they start to produce healthy blood cells. HSCT
does involve a number of risks, and complications can arise afterwards – some of
which are temporary, others of which can be life-threatening. Further information
about HSCT/BMT will be provided by the BMT centre, and families will have the
opportunity to discuss their concerns in detail with an immunologist and BMT
consultant on several occasions.

Gene therapy

Gene therapy aims to correct the underlying genetic abnormality by replacing
the faulty gene in immune cells with a normal copy. It is currently undergoing
clinical trials in selected patients who have certain specific conditions.

Thymic transplantation

Rarely, CID happens not because of a problem with the T cells themselves but
because of missing or faulty tissue in an organ called the thymus, where T cells
develop. The most common condition affecting thymus development is called
22q11 deletion syndrome (also known as DiGeorge syndrome). In the small
fraction (<1%) of DiGeorge patients whose thymus is completely missing, thymic
transplant may need to be considered. This is still an experimental treatment that
is only available at a few centres (Great Ormond Street Hospital in the UK). Further information about 22q11 deletion syndrome is available from the support organisation Max Appeal!

What does this mean for the future?

Continuing developments and improvements are transforming the lives of
children with CID. Better diagnostic techniques and genetic technology, better
treatments and better medications enable many children with CID to live healthy
lives pending curative therapy, such as stem cell transplant. It is likely that
new treatments, such as gene therapy, will continue to develop and become
applicable to more types of CID.

Reviewed November 2017