What are the types of protein S deficiency?

Updated: Jan 03, 2021
  • Author: Mohammad Muhsin Chisti, MD, FACP; Chief Editor: Perumal Thiagarajan, MD  more...
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Answer

In healthy individuals, approximately 30-40% of total protein S is in the free state. Only free protein S is capable of acting as a cofactor in the protein C system. This distinction between free and total protein S levels is important and gives rise to the current terminology regarding the deficiency states. Type I protein S deficiency is a reduction in the level of free and total protein S. Type III deficiency is a reduction in the level of free protein S only. Type II deficiency is a reduction in the cofactor activity of protein S, with normal antigenic levels.


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