Definition

Frameshift-causing mutations in exon 9 of the CALR (calreticulin) gene are found in about 30% of JAK2 and MPL mutation-negative ET/PMF patients, and in up to 50% of cases that lack both these genes. CALR-mutant ET is associated with a higher platelet count and lower risk of thrombosis/progression compared with JAK2 V617F.

Gene/Region Examined

CALR Exon 9

Method

DNA analysis

Accepted Sample Types

Bone marrow (EDTA)

Description

Myelofibrosis, somatic (Diagnosis).

Inheritance

Somatic; an acquired mutation in sporadic ET/PMF cases. Even in familial cases, it has been shown to arise somatically.

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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