Identification of zebrafish ortholog for human coagulation factor IX and its age-dependent expression.

Background: Coagulation factor IX (FIX) is a serine protease zymogen involved in the intrinsic blood coagulation pathway, and its deficiency causes hemophilia B. Zebrafish has three f9 genes, and the ortholog to human F9 is unknown.

Objective: To identify the zebrafish ortholog to F9 using sequence analysis and piggyback knockdown technology.