Clinical experience in T cell deficient patients

Table 1 Molecular defects that can present as SCID.

Disease	T cells	B cells	Immunoglobulin	Other features
Defect in cytokine signaling
Common γchain deficiency	↓↓	N or ↑	↓	Markedly decreased NK cells
IL7Rα deficiency	↓↓	N or ↑	↓	Normal NK cells
JAK3 deficiency	↓↓	N or ↑	↓	Markedly decreased NK cells
Defect in VDJ recombination
Artemis deficiency	↓↓	↓↓	↓
Cernunnos/XLF deficiency	↓	↓	↓	Microcephaly & radiation sensitivity
DNA ligase IV	↓	↓	↓	Microcephaly & radiation sensitivity
RAG1/2 deficiency	↓↓	↓↓	↓
Defects in TCR associated signaling
CD3δ/ε/ξ deficiency	↓↓	N	↓	Normal NK cells
CD45 deficiency	↓↓	N	↓	Normal γ/δ T cells
Disorders of purine metabolism
ADA deficiency	Absent from birth or progressive ↓	Absent from birth or progressive ↓	Progressive ↓	Neurological & Radiological features
PNP deficiency	Progressive ↓	N	N or ↓	Neurological & autoimmune features
Other defects
Reticular dysgenesis	↓↓	Normal or ↓	↓	Arrested myeloid maturation