DiGeorge is a genetic mutation in the development of _____ cells. SCID is a genetic mutation in the development of _____ cells. Bruton/X-linked Agammaglobulinemia is a genetic mutation in the development of _____ cells.
T
T or B (B cell is d/t VDJ inhibition)
B
Which congenital immunodeficiency is due to the absence of a thymus?
DiGeorge Syndrome
Which congenital immunodeficiency is due to inhibition of VDJ recombination in both B and T cell receptors?
SCID (due to defects in Pre-B and T cell receptors RAG 1 and RAG2)
Which congenital immunodeficiency is due to early mutation inhibiting the differentiation and activation of T cells?
SCID (X-linked)
Which congenital immunodeficiency is due to BTK mutations affecting pre-B cell maturation to mature B cells?
XLA (X-linked agammaglobulinemia)
T/F: SCID is sometimes caused by defects that completely abrogate the development of B lymphocytes
True; thought most of the time is the absence of T lymphocytes development! Sometimes, it could also affect NK lymphocytes
A young pt presents with severe infections, protracted diarrhea and failure to thrive:
Think SCID
What is mutated in X-linked SCID, and what is the result of that mutation?
X-linked recessive mutation of IL2RG genes which codes for gamma chain of many interleukin receptors, notably IL-7 (T cell maturation), IL-2 (T cell activation) and IL-15 (NK cell activation)
What is the inheritance pattern of the SCID that is deficient in adenosine deaminase?
Autosomal recessive
What happens with ADA deficiency SCID?
Adenosine deaminase is not present to break down purines, causing accumulation of dATP which inhibits DNA synthesis and T and B cells are very much mitotically active so they get heavily affected as a result
T/F: X-linked recessive SCID is due to mutation of the RAG1 and RAG2 genes
False; X-linked recessive SCID is due to mutation of IL2RG. The autosomal recessive defects in the pre-T cell receptor is due to mutation of RAG1 and RAG2
What is the significance of RAG1 and RAG2 genes?
Initiate the VDJ recombination process ultimately enabling generation of B and T cells with a diversified repertoire of antigen-specific receptors
What is the chromosomal deletion seen in DiGeorge Syndrome?