Definition

This is not a disease but a quality control method used in prenatal genetic testing; it detects the risk of a false result caused by maternal tissue mixing into the fetal sample (MCC) during CVS or amniocentesis. The method relies on PCR comparison of polymorphic STR loci in maternal and fetal DNA samples; contamination risk is approximately 0.5% in amniotic fluid samples and 1 to 2% in CVS samples.

Gene/region examined

STR analysis

Method

Fragment analysis

Accepted sample types

EDTA blood

Inheritance

Not applicable; this is a laboratory quality control procedure, not an inheritance pattern.

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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