Definition

The PLP1 gene encodes proteolipid protein 1, which makes up most of the myelin sheath in the central nervous system. Different variant types in this gene can cause two distinct diseases: duplications and certain point mutations lead to intracellular accumulation of the protein and severe loss of myelination (Pelizaeus-Merzbacher disease), while variants that disrupt only proteolipid protein 1 while preserving DM20 production cause the milder Spastic Paraplegia Type 2.

Gene/region examined

PLP1 - Exon 2, PLP1 - Exon 3, PLP1 - Exon 4, PLP1 - Exon 5, PLP1 - Exon 6, PLP1 - Exon 7

Method

Sequence analysis

Accepted sample types

EDTA blood, AF, CVS

Inheritance

Inherited in an X-linked manner and largely affects males; mothers are typically carriers.

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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