T-B+ severe combined immunodeficiency (SCID) [14 genes]

This form of severe combined immunodeficiency (SCID) is characterized by lack of functional peripheral T lymphocytes, and by normal levels of B lymphocytes although their function is compromised. In addition, these defects may be accompanied by absence of functional NK cells. SCID T-B+ is caused by alterations in different genes mainly involved in the maturation of T cells.

• 1/100,000 – 1/1,000,000 individuals
• 50% of SCID
• Common in Europe

• Differential diagnosis with BLS or agammaglobulinemia
• Genetic counseling
• Hematopoietic stem cell transplantation (HSCT)
• Gene therapy

Identifying a genetic defect responsible for the disease would allow a precise molecular diagnosis to be issued and make it possible to provide genetic counseling to the patient and their family members. In some cases, detecting a genetic variant can help explore specific treatment options.

In the case of severe combined immunodeficiencies, the treatment is usually bone marrow transplantation, but new emerging gene therapies open the door to other treatments that may be applied shortly.

• Severe life-threatening infections (viral, fungal, bacterial)
• Diarrhea
• Failure to thrive
• Autoimmunity
• Onset: neonatal, infancy