Factor IX (or Christmas factor) (EC 3.4.21.22) is one of the serine proteases of the coagulation system; it belongs to peptidase family S1. Deficiency of this protein causes hemophilia B. It was discovered in 1952 after a young boy named Stephen Christmas was found to be lacking this exact factor, leading to hemophilia.
Read more about Factor IX: Physiology, Domain Architecture, Genetics, Role in Disease
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“Children of the middle years do not do their learning unaffected by attendant feelings of interest, boredom, success, failure, chagrin, joy, humiliation, pleasure, distress and delight. They are whole children responding in a total way, and what they feel is a constant factor that can be constructive or destructive in any learning situation.”
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