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POR gene
Reviewed by Medicinsk Expert•Last updated: 2026-10-22•Gene

POR gene

The POR gene provides instructions for the enzyme cytochrome P450 oxidoreductase, which is vital for steroid hormone production, cholesterol synthesis, and drug metabolism.

Normal Function

The POR gene encodes the enzyme cytochrome P450 oxidoreductase. This enzyme is required for the function of over 50 enzymes in the cytochrome P450 family, which are responsible for:

  • Steroid hormone synthesis: Including testosterone, estrogen, corticosteroids, and aldosterone, which are essential for sexual development, stress response, and salt/water balance.
  • Cholesterol synthesis: Necessary for bone growth and development.
  • Drug metabolism: Processing medications in the liver.

Health Conditions Related to Genetic Changes

Cytochrome P450 oxidoreductase deficiency

Mutations in the POR gene significantly reduce the enzyme's activity, disrupting the production of steroid hormones and cholesterol. This leads to:

  • Disordered sexual development: Affecting both prenatal development and puberty.
  • Skeletal abnormalities: Impaired cholesterol production and the inability to break down retinoic acid can lead to abnormal bone growth and fusion.

The role of POR gene variations in how the liver processes medications remains an active area of research.

Other Names for This Gene

  • CPR
  • CYPOR
  • cytochrome P450 reductase
  • FLJ26468
  • NADPH-dependent cytochrome P450 reductase
  • NCPR_HUMAN
  • P450 (cytochrome) oxidoreductase
  • P450R

Frequently Asked Questions

Common signs include ambiguous genitalia at birth in both males and females, or incomplete pubertal development. Skeletal abnormalities can involve bent limbs, joint fusions (arthrogryposis), or abnormal bone development, particularly in the skull and face. Other symptoms may include adrenal insufficiency, leading to fatigue, low blood pressure, and salt cravings.
Skeletal abnormalities associated with POR gene mutations can range from mild to severe, including craniosynostosis (premature fusion of skull bones), radiohumeral synostosis (fusion of arm bones), and other joint fusions or malformations. Management typically involves orthopedic interventions, such as surgery to correct bone fusions or improve joint mobility, and physical therapy to maximize function and prevent further complications.
POR gene variant can significantly impair your body's ability to metabolize a wide range of medications, as the POR enzyme is crucial for many drug-processing P450 enzymes in the liver. This can lead to drugs staying in your system longer, increasing the risk of side effects, or being less effective. It is vital to inform all healthcare providers about your POR variant so they can adjust medication dosages, choose alternative drugs, and monitor for adverse reactions more closely.
Management of disordered sexual development due to POR gene mutations often involves a multidisciplinary team including endocrinologists, geneticists, and surgeons. Treatment may include hormone replacement therapy to induce puberty or manage adrenal insufficiency. Surgical interventions may be considered to align external genitalia with the assigned gender, but decisions are complex and made on an individual basis with extensive counseling.
Source: MedlinePlus, National Library of Medicine

MedlinePlus brings together authoritative health information from the National Library of Medicine (NLM), the National Institutes of Health (NIH), and other government agencies and health-related organizations.

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