The SCN9A gene instructs the production of the alpha subunit for the NaV1.7 sodium channel and the SCN10A gene instructs the production of the alpha subunit for the NaV1.8 sodium channel. Sodium channels transport positively charged sodium atoms (sodium ions) into cells and play a key role in a cells ability to generate and transmit electrical signals. The NaV1.7 and NaV1.8 sodium channels are found in nerve cells called nociceptors that transmit pain signals to the spinal cord and brain. The SCN9A gene mutations that cause small fiber neuropathy result in NaV1.7 sodium channels that do not close completely when the channel is turned off. Many SCN10A gene mutations result in NaV1.8 sodium channels that open more easily than usual. The altered channels allow sodium ions to flow abnormally into nociceptors. This increase in sodium ions enhances transmission of pain signals, causing individuals to be more sensitive to stimulation that might otherwise not cause pain. In this condition, the small fibers that extend from the nociceptors through which pain signals are transmitted (axons) degenerate over time. The cause of this degeneration is unknown, but it likely accounts for signs and symptoms such as the loss of temperature differentiation and pinprick sensation. The combination of increased pain signaling and degeneration of pain-transmitting fibers leads to a variable condition with signs and symptoms that can change over time. SCN9A gene mutations have been found in approximately 30 percent of individuals with small fiber neuropathy; SCN10A gene mutations are responsible for about 5 percent of cases.
Belatacept, sold under the brand name Nulojix, is a fusion protein composed of the Fc fragment of a human IgG1 immunoglobulin linked to the extracellular domain of CTLA-4, which is a molecule crucial in the regulation of T cell costimulation, selectively blocking the process of T-cell activation. It is intended to provide extended graft and transplant survival while limiting the toxicity generated by standard immune suppressing regimens, such as calcineurin inhibitors. It differs from abatacept (Orencia) by only two amino acids.Belatacept was developed by Bristol-Myers-Squibb and approved by the U.S. Food and Drug Administration (FDA) on June 15, 2011. References
External links
"Belatacept". Drug Information Portal. U.S. National Library of Medicine.