Definition

This is the sequencing of the protein-coding exon regions of the genome of a single individual (index/proband); it is used when a rare genetic disease of uncertain diagnosis is suspected, and diagnostic yield has been reported to range from 31.8% to 43% across various cohorts. Because only the proband sample is used, variant segregation cannot be assessed without parental data.

Method

Next-Generation Sequencing

Accepted sample types

EDTA Blood

Description

Analyzes exons and exon-intron junction regions belonging to ~22,000 gene regions. Investigates gene-level changes of unknown cause. Analysis depth is 100X coverage.

Inheritance

Studied in a germline context, an analysis performed on suspicion of hereditary/congenital disease.

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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