Definitive diagnosis* |
Patient less than 2 years of age with either (a) an absolute CD3 T cell count of less than 300/mm3, or (b) an absolute CD3 T cell count of greater than 300/mm3 with absent naïve CD3/CD45RA T cells, and at least 1 of the following: |
- Male with deleterious pathogenic variant in the X-linked IL2RG gene encoding the cytokine receptor common gamma chain (gamma-c).
|
- Male or female patient with deleterious homozygous or compound heterozygous pathogenic variants in any of the genes listed in the Gene Defects table other than IL2RG.
|
- ADA activity of less than 2% of control or pathogenic variants in both alleles of the ADA gene.
|
- Engraftment of transplacentally acquired maternal T cells.
|
Probable diagnosis* |
Male or female patient less than 2 years of age with (a) less than 20% CD3+ T cells, an absolute lymphocyte count of less than 3000/mm3, and proliferative responses to mitogens less than 10% of control or (b) the presence of maternal lymphocytes in the circulation. |