Definition

The PMM2 gene encodes phosphomannomutase 2, the enzyme that converts mannose-6-phosphate to mannose-1-phosphate; this enzyme is required in the N-linked glycosylation pathway. Its deficiency leads to faulty glycosylation of numerous glycoproteins, causing PMM2-CDG; findings include inverted nipples, abnormal fat distribution, developmental delay, cerebellar hypoplasia, and liver dysfunction; it is the most common of the known CDGs.

Gene/region examined

PMM2 - Exon 1, PMM2 - Exon 2, PMM2 - Exon 3, PMM2 - Exon 4, PMM2 - Exon 5, PMM2 - Exon 6, PMM2 - Exon 7, PMM2 - Exon 8

Method

Sequence analysis

Accepted sample types

EDTA blood, AF, CVS

Inheritance

Inherited, autosomal recessive.

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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