Evidence Based This post has 24 references
4.2 /5

CYP11A1 Enzyme Function, Genes & How to Increase/Decrease

Written by Biljana Novkovic, PhD | Last updated:

CYP11A1 is necessary for the production of steroid hormones, such as estrogen, testosterone, aldosterone, and cortisol. It converts cholesterol into pregnenolone, a precursor of all other steroid hormones. This enzyme also acts as an anti-inflammatory agent. However, it may increase susceptibility to allergies. Read on to learn more about CYP11A1 function, gene variants and factors that increase or decrease its activity.

What is CYP11A1?

This enzyme is also called the cholesterol side-chain cleavage enzyme or P450scc.

It is one of the cytochrome P450 monooxygenases (CYPs) [1]. CYPs eliminate toxins and drugs from the human body. However, some like CYP11A1, are not involved in detoxification but in steroid hormone production.

Read more about various CYPs here.


This enzyme is a key enzyme in steroid hormone production. It converts cholesterol to pregnenolone – from which all other hormones are derived [2, 3, 4, 5].

It also processes vitamins D2 and D3 [3, 6].

The activity of this enzyme is age and sex-dependent [7].


This enzyme is abundant in the adrenal gland, testis, ovary, and placenta [8, 9].

However, it is also active in the brain, skin, lungs, gut, bone, breast, and prostate [10].

Furthermore, it plays a function in the thymus and immune cells [10].

The Good

This enzyme is involved in steroid hormone production. It is necessary for testis development, pregnancy-related processes, and mating-related behavior [11].

In addition, CYP11A1 products act as anti-inflammatory agents. They decrease Th1/Th17 cytokines and NF-κB, while increasing IL-10 [10, 12].

Finally, there is evidence that CYP11A1 products have anti-cancer activity [10, 12].

Some of them show strong anti-tumor activity against breast cancer, liver cancer, glioma (brain cancer), and leukemia [10].

The Bad

This enzyme has a pro-allergic role. It favors the development of asthma and peanut-induced allergy in mice [13, 14, 15].

This is because steroid hormone production is an essential part of the Th2 response [15].

Decreasing the enzyme prevents allergic diarrhea and inflammation in mice [15].

Gene Polymorphism

People with partial or complete enzyme deficiency have adrenal insufficiency [2]. This is a condition in which the adrenal glands do not produce adequate amounts of steroid hormones.

They also have sexual development disorders [2].

Lifelong hormone replacement therapy is necessary for this condition. Without therapy the disease is lethal [16].

The condition is rare. So far, only 19 patients with CYP11A1 complete deficiency-causing mutations have been reported worldwide [17].

  • RS2279357

rs2279357 was associated with autism spectrum disorder (100 families) [18].

Women with rs2279357 T/T are more prone to develop breast cancer (530 patients and 546 controls) [19].

  • RS11632698

rs11632698 was associated with aromatase-inhibitor-related bone loss (391 breast cancer patients) [20].

  • (TTTTA)n variant

A five nucleotide repeat variant in CYP11A1, when repeated four times (TTTTA)4, increases the risk of polycystic ovary syndrome (PCOS) (meta-analysis, 1,236 patients, and 1,306 controls) [21].

On the other hand, having a (TTTTA)6 variant, with 6 repeats, decreases the risk of polycystic ovary syndrome (PCOS) (meta-analysis, 1,236 patients, and 1,306 controls) [21].

People with (TTTTA)6 may have an increased risk of metastatic and high-grade prostate cancer (206 subjects) [22].

Increasing or Decreasing CYP11A1

These increase CYP11A1

  • Ginseng (Panax ginseng) [11]
  • UVB and UVC [10]
  • Bisphenol A (BPA) [23]
  • Pemirolast, clobenpropit, desogestrel, dexmedetomidine, and tizanidine [24]

These decrease CYP11A1:

  • Ketoconazole, posaconazole, carbenoxolone, and selegiline [24]

About the Author

Biljana Novkovic

Biljana Novkovic

Biljana received her PhD from Hokkaido University.
Before joining SelfHacked, she was a research scientist with extensive field and laboratory experience. She spent 4 years reviewing the scientific literature on supplements, lab tests and other areas of health sciences. She is passionate about releasing the most accurate science and health information available on topics, and she's meticulous when writing and reviewing articles to make sure the science is sound. She believes that SelfHacked has the best science that is also layperson-friendly on the web.


1 Star2 Stars3 Stars4 Stars5 Stars
(5 votes, average: 4.20 out of 5)

FDA Compliance

The information on this website has not been evaluated by the Food & Drug Administration or any other medical body. We do not aim to diagnose, treat, cure or prevent any illness or disease. Information is shared for educational purposes only. You must consult your doctor before acting on any content on this website, especially if you are pregnant, nursing, taking medication, or have a medical condition.

Leave a Reply

Your email address will not be published. Required fields are marked *

Related Articles View All