Definition

The Factor V Leiden component of these panels is covered in the glossary as a separate term. The panel-specific Factor II (Prothrombin) G20210A variant increases the circulating amount of prothrombin protein, making blood more prone to clotting; heterozygous carriers have a several-fold increased risk of thrombosis, but most carriers never develop thrombosis. The MTHFR C677T/A1298C variants that are frequently added to such panels have not been shown by current evidence to increase the risk of venous thromboembolism; ACMG has stated that these variants should not be ordered as part of routine thrombophilia evaluation.

Gene/region examined

Factor II G20210A, Factor V Leiden, MTHFR A1298C, MTHFR C677T

Method

Sequence analysis

Accepted sample types

EDTA blood

Inheritance

Prothrombin thrombophilia is inherited in an autosomal dominant manner; carrying a single mutant copy is sufficient, and the chance of transmission from a heterozygous parent to a child is 50 percent.

Related Tests

Inheritance Patterns

Describes how a genetic condition is passed on within a family. There are five main patterns

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Carrier (Heterozygous / Homozygous)

Why it matters: In autosomal recessive inheritance, when each parent is a carrier (while both appear healthy), the chance of their child being born with the disease is 25% in each

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VUS (Variant of Uncertain Significance)

This is the situation where the test has detected a change in the DNA, but the role of this change in the development of disease is unconfirmed.

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How to Read a Genetic Test Result (Positive / Negative / VUS)

A genetic test result falls into three main categories

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Types of Genetic Tests

A genetic test is a type of medical test that detects changes in genes, chromosomes or proteins. Today there are more than 77,000 genetic tests available.

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