T-Cell Immunodeficiencies: Hyper IgM Syndrome, Wiskott-Aldrich Syndrome and MHC Class II Deficiency – Primary Immunodeficiency

Examples of immunodeficiencies affecting T-cells are listed here. So for example, a defective gene for the CD40 ligand, or for CD40 itself, or for AID or for NEMO or for UNG, result in a condition called hyper-IgM syndrome. And you can read through this list for yourself. You can see a number of different gene defects causing a number of different consequences. In hyper-IgM syndrome, there is raised serum IgM and IgD. You’re probably thinking, hang on a minute, I thought we were talking about immunodeficiency? And yet you’re telling me that there is raised serum IgM and IgD, that there’s more. Hyper-IgM it sounds good doesn’t it? You got more IgM than other people. But the problem is, that there is very low or absent IgG, IgA and IgE. Most patients have an X-linked form of the hyper-IgM syndrome, in which there is a defect in the gene encoding CD40 ligand. Less commonly, there is a defect in the gene encoding a molecule called NEMO, which is the NF𝜅B essential modifier, sometimes known as IKKγ. And in some patients there is a defect in the gene encoding CD40, which is an autosomal gene or in the gene encoding the activation-induced cytidine deaminase (AID) or in the gene encoding uracil-DNA glycosylase (UNG). The result is recurrent bacterial infections. There is also a condition called Hyper-lgE Syndrome and in this condition there is immune dysregulation with an increase in the level of lgE antibody as the name suggests Hyper-lgE Syndrome. An increase in the number of eosinophils, B-cells and natural killer cells but a decrease in CD8+ T-cell proliferation and activation. There are autosomal dominant mutations in STAT3 or autosomal recessive mutations in TYK2 or DOCK8. STAT3 and TYK2 are involved in signaling through several different cytokine receptors. DOCK8 deficiency results...