Abstract: This study aimed to investigate the association of factor V gene (F5  ( single nucleotide
polymorphism (SNP) with the incidence of thrombosis related to the Leiden in Iraqi patients. Blood
samples were collected from one hundred patients attending (AL Yarmook Teaching Hospital and
AL Kadhimiya Teaching Hospital) Baghdad / Iraq, as well as from 100 healthy subjects served as
control group.  Serum samples were analyzed using troponin test (TNT) for detection of thrombosis.
This study found that age group 50 to 60 years old showed thrombosis 45% more than younger once,
and the thrombosis was more frequent in males 55% than females 45% (P<0.01).   Polymerase chain
reaction showed that 28 pathogenic SNPs in DNA led to Leiden mutation identified among patients
as missense and additional open reading frame in mutated sequence.