Definition

Mutations in JAK2 exon 12 identify a subgroup of patients with V617F-negative polycythemia vera or idiopathic erythrocytosis. These patients show isolated erythrocytosis, absence of leukocytosis/thrombocytosis, low serum erythropoietin levels, and isolated erythroid hyperplasia in the bone marrow.

Gene/region examined

JAK2 exon 12

Method

DNA analysis

Accepted sample types

Blood (EDTA), bone marrow (EDTA)

Description

Monitoring response to drug treatment and relapse in various cancer types.

Inheritance

This is somatic; it is an acquired clonal mutation similar to V617F, but produces a different clinical phenotype (isolated erythrocytosis).

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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