Prothrombin 20210A Allele (PT20210A)

Coagulation

Description

A single nucleotide change of guanine to adenine at position 20210 in the 3' untranslated region of the prothrombin ( factor II ) gene results in increased plasma prothrombin levels and a 2-3 fold increased risk of venous thrombosis.

Heterozygous prothrombin G20210A results in a 2-3 fold increased risk of venous thrombosis, risk is further increased risk if homozygous or in the presence of other risk factors. Prothrombin G20210A causes increased synthesis of factor II.

Indications

As a part of the thrombophilia screen. Approximately 1-2% of the UK population is heterozygous for this polymorphism and guidelines recommend against family investigations of prothrombin G20210A in relatives. It is recommended that if the result is homozygous, the test should be checked on a second occasion.

Sample Type

Whole blood (Citrate Blue or EDTA Purple) x 1

Reference Range

Presence or absence of mutation indicated on report.

Turnaround Time

Within 2 weeks

Testing Frequency

Weekly

External Notes

Results Prothrombin 20210A absent (normal) or abnormal due to presence of mutation (heterozygous or homozygous) indicated on the report. It is recommended that if the result is result is homozygous, the test should be checked on a second occasion.

Patient Preparation

Specimens must not be taken into heparinised tubes as high concentration of heparin can cause the assay to fail; however, therapeutic levels of heparin will not affect the assay.

References

Baglin et al; British Committee for Standards in Haematology. Clinical guidelines for testing for heritable thrombophilia. Br J Haematol. 2010 Apr;149( 2 ):209-220
Cooper et al, Evaluation of the Roche LightCycler: a simple and rapid method for direct detection of factor V Leiden and prothrombin G20210A genotypes from blood samples without the need for DNA extraction. Blood Coagul Fibrinolysis. 2003 Jul;14(5):499-503.

Your contact for this test

Kieron Hickey

Thrombophilia Section Lead and Deputy Laboratory Manager - Coagulation

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Prothrombin 20210A Allele (PT20210A)