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6907: Severe Combined Immune Deficiency: Prospective and Longitudinal Study of Genotypes, Management and Outcomes


Severe combined immune deficiency (SCID) is a condition in which patients fail to develop a normal complement of T cells as well as functional B cells. Left untreated, these missing critical components of the immune system lead to an increased frequency and severity of infections with a high risk of death early in life. SCID is caused by mutations in a gene responsible for T cell development; there are over twenty known genetic subtypes of SCID. SCID is now commonly diagnosed in the first month of life, often in an asymptomatic state, through newborn screening of heel-stick dried blood spots. SCID may be treated by allogeneic hematopoietic cell transplantation, experimental autologous gene therapy, or (in the case of SCID due to mutations in the ADA gene), enzyme-replacement therapy.

About this Study

Individuals with a possible diagnosis of severe combined immune deficiency (including infants who were identified by newborn screening) may be eligible to be enrolled on the PIDTC research study 6907. Speak to your doctor to determine if you / your child may be eligible.  Protocol 6907 follows all patients with SCID, meaning the 6907 study enrolls participants regardless of whether they have already received a blood and marrow transplant (BMT), enzyme replacement therapy (ERT), or gene therapy (GT). Patients are then followed after diagnosis and treatment according to standard of care recommendations, which typically align with a schedule set out by the study protocol. The times the study requests follow up will be the same as when your doctor would want to be seeing you / your child as part of their regular ongoing medical care. Patients with “leaky SCID” (a form of SCID with T cell numbers less severely compromised) and Omenn syndrome are also eligible to participate in 6907. The 6907 research study does NOT dictate how your / your child’s doctors should treat you / your child, as the PIDTC recognizes that there are many complex factors that go into this decision.  The decision about how you / your child with SCID will be treated is made by your doctor.  The 6907 study simply follows how you / your child do over time.  There are no experimental therapies on this study.

6907 has been open since the Fall of 2021 and continues to be open and enrolling patients to the present day.  The study plans to enroll approximately 450 patients with SCID.  By studying patients prior to and undergoing treatment for SCID, the goal is to learn more about: (1) outcomes from the treatment of SCID in the modern era of medicine (2) what factors lead to the best long-term outcomes, such as best donor, conditioning regimen, timing of transplant, etc. (3) what impact newborn screening and the early diagnosis of SCID has had on the long-term outcomes following BMT or gene therapy.  A significant amount of information is also being gathered on how and when the immune system recovers after BMT, quality of life for long-term survivors, and about whether children develop normally after treatment.

6907 is the largest coordinated study of patients with SCID ever performed, and will built on the information learned from the prior two PIDTC SCID studies, 6901 and 6902.  Information that we will learn, both now and in the future, will help doctors and other health professionals to better treat children with SCID.  All hospitals within the PIDTC are enrolling patients with SCID on 6907, ensuring that the outcomes are reflective of what happens in the “real world” as opposed to at just one or two large centers. 

Targeted Enrollment

To be eligible to participate, you / your child must:

  • Be an individual with all of the following:
  • Have a suspicion of SCID, due to low TRECs. If an alternate diagnosis to SCID is confirmed, the patient will be removed from the study.
  • Have a diagnosis of SCID, including:
  • Typical SCID
  • Leaky SCID
  • Omenn syndrome

You are not eligible to participate if:

  • A participant should not be in the study if any of the following are present:
  • HIV Infection
  • DiGeorge syndrome
  • Combined Immunodeficiency Disorders
  • MHC Class I or II Deficiencies