Gene Therapy for X-Linked Severe Combined Immunodeficiency (SCID-X1)

Severe combined immunodeficiency (SCID), often referred to as “bubble boy disease,” is a rare hereditary condition that makes infants vulnerable to infection. Essentially, children with SCID lack an immune system.

SCID is caused by genetic mutations. In the most common form of the disease, X-linked SCID (SCID-X1), the gene responsible is IL2RG, which is needed for the healthy development of several kinds of immune cells — T and natural killer lymphocytes and nonfunctional B lymphocytes. The current treatment for SCID-X1 is a bone marrow transplant that can produce normal immune cells, but finding a suitable can be a challenge.

How gene therapy for SCID-X1 works

To perform SCID-X1 gene therapy, a patient’s blood stem cells (these are the cells that give rise to all mature blood stem cells) are collected. In a highly-specialized laboratory, a viral vector is used as a carrier to insert a correct version of the faulty IL2RG gene into the patient’s stem cells. Then, the patient receives chemotherapy to make room for the genetically-altered cells. Finally, the cells are given back to the patient via an intravenous infusion.

Illustration of SCID-X1 gene therapy


SCID-X1 gene therapy clinical trial

Phase I/II Trial of Lentiviral Gene Transfer for SCID-X1 With Low Dose Targeted Busulfan Conditioning
Recruiting males up to 5 Years (full eligibility criteria)
Boston Children’s Hospital

Started: Jan. 2018

Principal investigators: Sung-Yun Pai, MD, and David A. Williams, MD,
Colleen Dansereau, MSN, RN, CPN617-919-7008 or colleen.dansereau@childrens.harvard.edu

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