TABLE 1.

Genotypic and phenotypic differences in SCID and R2G2 mice. Strain-dependent underlying genotype defects, immunodeficiency, and radiosensitivity profiles differ between mouse strains.

MOUSE STRAIN	GENOTYPE DEFECT	IMMUNODEFICIENCY	RADIOSENSITIVITY
SCID	Disrupted Protein Kinase, DNA-Activated, Catalytic Subunit gene (prkdc, DNA damage sensor)	++ Impaired T & B cell development “Leaky” immunity	+++ Disrupted double-stranded DNA repair
R2G2	Double-knockout Recombination activating gene 2 (Rag2, essential for making mature T & B cells) Common gamma chain gene (IL2rg, a component of many interleukin receptors)	++++ Defective lymphocyte development and disrupted interleukin receptors. “Non-Leaky” immunity	−/+ Maintained DNA repair