GENE REFERENCE / HGNC:9208

POR

cytochrome p450 oxidoreductase

protein-coding gene7q11.23Gene information

What does this gene do?

The POR gene provides instructions for making the enzyme cytochrome P450 oxidoreductase. This enzyme is required for the normal functioning of more than 50 enzymes in the cytochrome P450 family. Cytochrome P450 enzymes are involved in the formation (synthesis) and breakdown (metabolism) of various molecules and chemicals within cells.

Cytochrome P450 enzymes are critical for the synthesis of cholesterol and steroid hormones. Cholesterol is a substance that has many essential functions both before and after birth, including roles in the production of steroid hormones and in the formation and growth of bones. Steroid hormones are needed for normal development and reproduction. This group of hormones includes testosterone and estrogen, which are essential for normal sexual development and reproduction; corticosteroids, which are involved in the body's response to stress; and aldosterone, which helps regulate the body's salt and water balance.

Additionally, cytochrome P450 enzymes are involved in the metabolism of ingested substances, such as medications, in the liver. Because cytochrome P450 oxidoreductase helps regulate the activity of these enzymes, researchers suspect that normal variations in the POR gene may influence a person's response to particular drugs (drug metabolism).

Source: MedlinePlus, National Library of Medicine. Source publication: 2020-08-18. Source review: 2014-02.

ClinGen reviews

ClinGen reviews the evidence linking a particular gene to a condition. Each rating below describes the strength of that link. It does not classify a variant in your DNA file.

Condition	Inheritance	Evidence
Antley-Bixler syndrome with genital anomalies and disordered steroidogenesisMONDO:0008726 · Evaluated 2022-03-23	Autosomal recessive	DefinitiveCraniofacial Malformations Gene Curation Expert Panel

ClinVar records

These numbers show what has been submitted to ClinVar. They cannot tell you how likely you are to have a condition.

Submitted alleles: 1,036
Submissions for variants in or overlapping this gene: 1,642
Submissions explicitly reporting this gene: 1,549
Alleles reported pathogenic / likely pathogenic: 115
VariationIDs with uncertain significance: 284
VariationIDs with conflicting classifications: 68

The rows count different things: alleles, submissions or VariationIDs. Their categories can overlap, so do not add them together. Pathogenic/likely pathogenic counts exclude structural variants that merely overlap a gene. A dash in the source means “not reported,” not zero.

NCBI produces the gene-summary file each week using counts recorded at the start of the month. The numbers may differ from those on the live ClinVar website. Read the field definitions ↗

View this gene in ClinVar ↗

YOUR DNA FILE

Can your DNA file tell you about POR?

From a DNA test kit (such as 23andMe, AncestryDNA or MyHeritage). These kits check a fixed list of about 600,000 to 700,000 positions across your whole genome. ClinVar lists 115 alleles in POR reported as pathogenic or likely pathogenic. A kit checks only some of these positions, and often none of them.

From whole genome sequencing (a VCF file). Sequencing reads most of your genome. Your file lists the places where your DNA differs from the reference genome. Some regions are hard to sequence, including parts of some genes that have near-identical copies elsewhere, and a VCF file does not record which positions were read well.

If a variant is not in your file, that does not mean you don’t have it.

What BioDecode checks

BioDecode compares every variant in your file with ClinVar, on your own computer. For each match, it shows the ClinVar classification, the review status and the condition it was reported for. Your file is not uploaded.

A ClinVar classification applies to one particular variant and the condition it was reported for. It does not tell you about other variants in POR.

BioDecode cannot fill gaps in your test, diagnose a condition or replace clinical testing.

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