TNFRSF1A

More than 60 mutations in the TNFRSF1A gene have been found to cause tumor necrosis factor receptor-associated periodic syndrome (commonly known as TRAPS). Most of these mutations lead to changes in single protein building blocks (amino acids), typically involving the amino acid cysteine. Cysteines contain sulfur atoms that form connections, called disulfide bonds, with other cysteines. Disulfide bonds help a protein fold by connecting cysteines in different regions of the protein. These bonds stabilize the protein and give it the appropriate shape to carry out its particular function.

When cysteines within the TNFR1 protein are replaced with other amino acids, the disulfide bonds are not formed, and the protein is misfolded. These misfolded proteins are trapped within the cell, unable to get to the cell surface to interact with TNF. Inside the cell, these proteins clump together and are thought to trigger alternative pathways that initiate inflammation. The clumps of protein constantly activate these alternative inflammation pathways, leading to excess inflammation in people with TRAPS. Additionally, because only one copy of the TNFRSF1A gene has a mutation, some normal TNFR1 proteins are produced and can bind to the TNF protein, leading to additional inflammation. It is unclear if disruption of the apoptosis pathway plays a role in the signs and symptoms of TRAPS.

Some people with mutations in the TNFRSF1A gene do not develop TRAPS, or they develop very mild features of the disorder. The reason for this variability is unclear, but researchers believe that other factors, such as additional genetic changes or environmental factors, may play a role in causing TRAPS.

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