Definition

Heterozygous pathogenic variants in the TNNI3 gene disrupt cardiac troponin I, a component of the sarcomere's calcium-dependent contraction regulatory complex, and can lead to a broad phenotypic spectrum including familial hypertrophic cardiomyopathy, familial restrictive cardiomyopathy, and dilated cardiomyopathy. Missense variants are generally associated with a dominant hypertrophic/restrictive phenotype, while biallelic null variants have been linked to severe neonatal dilated cardiomyopathy.

Gene/region examined

TNNI3 - Full Gene

Method

Sequence analysis

Accepted sample types

EDTA blood, AF, CVS

Inheritance

Inherited, mostly autosomal dominant (missense variants); the severe neonatal dilated form caused by biallelic null variants can show autosomal recessive inheritance.

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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