Definition

The most common known cause of monogenic obesity is mutations in the gene encoding the melanocortin-4 receptor (MC4R), which transmits the satiety signal in neurons of the hypothalamus. MC4R deficiency is characterized by severe obesity, increased lean body mass, accelerated growth in early childhood, hyperphagia, and marked hyperinsulinemia; an MC4R mutation is detected in about 6% of patients with severe early-onset obesity.

Gene/region examined

MC4R - Whole Gene

Method

Sequence analysis

Accepted sample types

EDTA blood, AF, CVS

Inheritance

Hereditary, codominant (MC4R haploinsufficiency); fully recessive forms have also been reported.

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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