Definition

Familial hypercholesterolemia type 1 is characterized by pathogenic variants in the LDLR gene resulting in an absent or nonfunctional LDL receptor on the surface of hepatocytes; LDL particles cannot be adequately cleared from the circulation. LDL cholesterol can reach 190 to 400 mg/dL in heterozygotes and 400 to 1000 mg/dL in homozygotes; the risk of a coronary event before the fourth decade of life is markedly increased in untreated men.

Gene/region examined

LDLR - Whole Gene

Method

Sequence analysis

Accepted sample types

EDTA blood, AF, CVS

Inheritance

Inherited, autosomal dominant (gene dosage effect: a much more severe phenotype in homozygotes/compound heterozygotes).

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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