Mice homozygous for the severe combined immune deficiency spontaneous mutation (Prkdcscid, commonly referred to as scid) are characterized by an absence of functional T cells and B cells, lymphopenia, hypogammaglobulinemia, and a normal hematopoietic microenvironment. Normal antigen-presenting cell, myeloid and NK cell functions are strain dependent. scid mice carry a DNA repair defect and a defect in the rearrangement of genes that code for antigen-specific receptors on lymphocytes. Most homozygotes have no detectable IgM, IgG1, IgG2a, IgG2b, IgG3, or IgA. Thymus, lymph nodes, and splenic follicles are virtually devoid of lymphocytes. scid mice accept allogeneic and xenogeneic grafts making them an ideal model for cell transfer experiments. Some scid mice will spontaneously develop partial immune reactivity. scid mice that have serum Ig levels greater than 1 ug/ml are considered "leaky." scid leakiness is highly strain dependent, increases with age, and is higher in mice housed under non SPF conditions. In general, scid leakiness is high on the C57BL/6J and BALB/cBy genetic backgrounds, low on the C3H/HeJ background, and even lower on the NOD/LtSz background. In addition to the effects of the scid mutation, GhrhrlitPrkdcscid /Bm mice are deficient in growth hormone and IGF1 while GhrhhpgPrkdcscid/Bm mice (Stock No. 002038) are deficient in gonadotropins and gonodal steroids. These two double mutant strains are useful for determining endocrine dependence of grafted cells and tissues.
C57BL/6J-Ghrhrlit/Ghrhrlit x C.B-17-Prkdcscid/Prkdcscid offspring were sibling mated. The strain was made homozygous for Prkdcscid and kept segregating for Ghrhrlit and the sibling mating continued to the present.
|Allele Synonym(s)||lit; litm|
|Gene Symbol and Name||Ghrhr, growth hormone releasing hormone receptor|
|Strain of Origin||C57BL/6J|
|Molecular Note||The mutation in little mice is a A-to-G transition in codon 60 that alters this residue from a aspartate to a glycine in the encoded protein (p.D60G). Reduced levels of mRNA were noted in total RNA derived from pituitary of homozygous mice, and in vitro assays demonstrated that no functional protein is made from this allele.|
|Allele Name||severe combined immunodeficiency|
|Gene Symbol and Name||Prkdc, protein kinase, DNA activated, catalytic polypeptide|
|Site of Expression||T and B lymphocytes.|
|Strain of Origin||C.BKa-Ighb/Icr|
|Molecular Note||A T-to-A transversion point mutation at a position corresponding to codon 4046 (codon 4095 in transcript ENSMUST00000023352.8) created a premature stop codon (p.Y4046*).|