Prothrombin which is also called Factor II, is a protein in the blood involved in the blood clotting mechanism. It is needed to form fibrin which is then required for blood clotting. Recently, a new polymorphism in the 3’ untranslated region of the prothrombin gene (F2), guanine 20210 adenine mutation is described which alters the polyadenylation site of the gene resulting in excess mRNA synthesis with subsequent increased protein expression. That is found to be associated with elevated levels of prothrombin and results in increased risk for hypercoagulability disorders (thrombophilia). [1], [2], [3]
The G20210A is the second more frequent variant implicated in hypercoagulability disorders of the caucasian population and has the prevelance of approximately 1 to 4% in the normal population. It is more prevalant in southern European and rarely seen in Asians or Africas. [4] A study of patients in Turkey revealed the presence of the prothrombin 20210a mutation in 0.7% of subjects.[5] The G20210A variant, an autosomal recessive deficiency, which is usually not accompanied by other factor mutations ( i.e. Factor V-Leiden) may be inherited heterozygous (1 pair), or rarely, homozygous (2 pairs), and not mainly related to gender or blood type. Also with other risk factors; including congenital thrombophilia (deficiency of protein C and protein S etc.), temporary factors such as surgery, immobility, pregnancy and chronic conditions such as obesity and cancer, homozygous mutations increase the risk of thrombosis more than heterozygous mutations. [6]
The diagnosis of a prothrombin mutation is made by a blood test that requires DNA analysis of F2, gene encoding prothrombin, to identify the common substitution, a G>A transition at nucleotide 20210A. Although simply applying a test of prothrombin concentrations in plasma may give an idea about prothrombin mutation, it is the molecular test with satisfying and reliable results allowing to success genotypic identification. [7]
