What is the role of bone marrow transplantation in the treatment of severe combined immunodeficiency (SCID)?

Updated: Apr 28, 2021
  • Author: Robert A Schwartz, MD, MPH; Chief Editor: Harumi Jyonouchi, MD  more...
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Although treatment of the acute infectious process is critical, the only cure for almost all forms of SCID is bone marrow transplantation or other stem cell reconstitution. [42, 43] This approach is successful if the disease is diagnosed within the first 3 months of life. Early transplantation before 3.5 months is associated with better overall survival. [44] With early transplantation and aggressive monitoring and treatment of infections, survival rates may be as high as 97%. No live vaccines should be administered before BMT.

The optimal bone marrow donor is a human leukocyte antigen (HLA)–matched sibling or parent if consanguinity is present. Haploidentical parent donors, HLA-matched unrelated donors, and HLA 5/6 allele–matched unrelated donors have also been successful; however, the risk for graft failure, GVHD, and inadequate B-cell function is higher. Neither pretransplant chemoablation nor GVHD prophylaxis is required for successful engraftment with an identical donor; however, the former is necessary with nonidentical HLA-matched donors.

Pretransplant evaluation routinely includes testing of the recipient and the donor for infectious agents, such as cytomegalovirus (CMV), HIV, and hepatitis viruses. After BMT, medication therapy to prevent GVHD must be maintained. [45] All blood products must receive 25-Gy irradiation to prevent fatal GVHD.

BMT is the primary therapy for purine nucleotide phosphorylase (PNP) deficiency and bare lymphocyte syndrome when an appropriate donor is available. It is also the primary treatment for Omenn syndrome; however, pretreatment ablative chemotherapy is necessary because of maternal cell engraftment.

In the largest series of patients with SCID, BMT was successful in 80% of patients. T-cell function has been adequate in approximately 90% of patients who survive 6 months after transplantation, and B-cell function has been adequate in 70% of these patients. Workup includes major histocompatibility complex (MHC) typing to identify a fully matched sibling, or, in the case of consanguinity, possibly a parent.

In utero BMT into the fetal peritoneal cavity is successful, with reconstitution of T-cells in X-linked SCID (XL-SCID) and in 1 case of due to interleukin (IL)-7 receptor α chain deficiency. Cord blood stem cell transplantation from related or unrelated donors is an option.

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