Therefore, co-infection with microbes that carry PAMPs may be necessary for the initial onset of symptoms in gluten sensitivity, but would not be necessary for successive encounters with gluten due to the production of memory B and memory T cells (discussed below). Dermatitis herpetiformis may be characterised based on inflammation in the skin and gut. Inflammation in the gut is similar to, and linked to, celiac disease. tTG is treated as an autoantigen, especially in people with certain HLA-DQ2 and HLA-DQ8 alleles and other gene variants that cause atopy. tTG is up-regulated after gluten absorption. cDCs endocytose tTG-modified gliadin complexes or modified gliadin alone but they only present gliadin to CD4+ T cells on pMHC-II complexes. These T cells become activated and polarised into type I helper T (Th1) cells. Th1 cells reactive towards gliadin have been discovered, but none against tTG. A naive B cell sequesters tTG-modified gliadin complexes from the surface of cDCs in the lymph nodes (LNs) before they become endocytosed by the cDCs. The B cell receptor (membrane bound antibody; BCR) is specific to the tTG portion of the complex. The B cell endocytoses the complex and presents the modified gliadin to the activated Th1 cells T cell receptor (TCR) via pMHC-II in a process known as epitope spreading. Thus, the B cell presents the foreign peptide (modified gliadin) but produces antibodies specific for the self-antigen (tTG). Once the B cell becomes activated, it differentiates into plasma cells that secrete autoantibodies against tTG, which may be cross-reactive with epidermal transglutanimase (eTG).
Hypervalinemia is a rare autosomal recessive metabolic disorder in which urinary and serum levels of the branched-chain amino acid valine are elevated, without related elevation of the branched-chain amino acids leucine and isoleucine. It is caused by a deficiency of the enzyme valine transaminase. Presentation
Presenting in infancy, symptoms include lack of appetite, vomiting, dehydration, hypotonia and failure to thrive. Genetics
Hypervalinemia is inherited in an autosomal recessive manner. This means the defective gene responsible for the disorder is located on an autosome, and two copies of the defective gene (one inherited from each parent) are required in order to be born with the disorder. The parents of an individual with an autosomal recessive disorder both carry one copy of the defective gene, but usually do not experience any signs or symptoms of the disorder. Diagnosis
See also
Isovaleric acidemia
Maple syrup urine disease
Propionic acidemia

References


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