Definition

Cryptic rearrangements occurring in the subtelomeric regions of chromosome 17 are investigated in cases of unexplained intellectual disability/developmental delay; deletions in the terminal 17p13.3 region affect the PAFAH1B1 (LIS1) gene and can lead to the lissencephaly/Miller-Dieker syndrome spectrum. It explains approximately 5% of idiopathic intellectual disability cases.

Method

FISH analysis

Accepted sample types

Heparinized blood

Inheritance

Mostly de novo; can be familial when caused by a parent's balanced translocation carrier status.

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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