Definition

The DPYD gene encodes the enzyme dihydropyrimidine dehydrogenase (DPD); DPD is the rate-limiting first step in the metabolism of 5-fluorouracil (5-FU) and capecitabine. In patients with reduced DPD activity, drug clearance falls, the half-life is prolonged and the risk of serious, potentially fatal dose-dependent toxicity (severe neutropenia, mucositis, neurotoxicity) increases. The CPIC guideline recommends a 50% reduction of the starting dose in patients heterozygous for a decreased-function/no-function variant.

Gene/region examined

DPD

Method

Mini Sequencing

Accepted sample types

Peripheral blood (EDTA)

Inheritance

Germline/inherited; DPYD variants are carried from birth and are not somatic changes specific to tumor tissue.

Related Tests

Inheritance Patterns

Describes how a genetic condition is passed on within a family. There are five main patterns

Go to term →

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

Go to term →

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.

Go to term →

How to Read a Genetic Test Result (Positive / Negative / VUS)

A genetic test result falls into three main categories

Go to term →

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.

Go to term →