TEST DETAILS

Androgen Receptor — CAG trinucleotide repeat length Test

Learn about your individual sensitivity to anobolic steroids

male hormone responsesteroid resistancetestosterone levels

What gene we test?

Androgen receptor gene (commonly shortened to AR)

Scientific name

Androgen receptor (AR) — CAG (cytosine, adenine, and guanine) trinucleotide repeat length encoding a polyglutamine tract within the AR

What does it do?

The androgen receptor is a protein in your cells that helps your body respond to male hormones like testosterone. When testosterone interacts with the AR protein it moves into the cell's control centre and turns on or off certain genes regulating muscle mass, bone density, and other male traits. The CAG repeat is a stretch of DNA encoding glutamine amino acids in this AR protein that comes in different lengths (usually 4 to 43 copies). Shorter stretches make change the way in which the receptor works leading to stronger responses to male hormones and lower natural testosterone levels in the blood. Longer stretches make it work less efficiently, weakening the response but often raising blood testosterone levels as the body tries to compensate. The AR protein is encoded by a gene (the blueprint for building the protein) on the X Chromosome.

Variants overview

Short - Stronger receptor action; better response to male hormones and lower blood testosterone
Long - Weaker receptor action; poorer response to male hormones and higher blood testosterone

Variant Risk Wheel

Detailed Variant Information

Low (less than 27 CAG repeats) Variant

Frequency

~93%

Effect

People with short CAG repeats have a receptor that works most effectively, giving a stronger response to male hormones, lower chance of steroid resistance, and usually lower natural testosterone levels in the blood; little effect on how steroids work.

Simple explanation

Short repeats boost your body's reaction to male hormones and keep natural testosterone lower.

What this means

Short CAG repeats make your receptor respond at high to average levels, and your risk may be more in line with the general population.

Intermediate (27-35 CAG repeats) Variant

Frequency

~7%

Effect

People with intermediate CAG repeats have a receptor that works less effectively, raising the chance of steroid resistance, weaker response to testosterone or anabolic androgenic steroids, and usually higher natural testosterone levels in the blood.

Simple explanation

Intermediate repeats give a standard reaction to male hormones and normal testosterone levels.

What this means

Intermediate CAG lengths mean your receptor functions typically, with no big boosts or drops in hormone response.

High (more than 35 CAG repeats) Variant

Frequency

<0.1% (rare)

Effect

People with long CAG repeats have a receptor that works significantly less effectively, raising the chance of steroid resistance, significantly weaker response to testosterone or anabolic androgenic steroids, and usually significantly higher natural testosterone levels in the blood.

Simple explanation

Long repeats dull your body's reaction to male hormones but may raise natural testosterone significantly.

What this means

Long CAG repeats make your receptor significantly less responsive, so male hormones might not have as strong an effect even if your blood levels are significantly higher.

Included in panels

Starter Panel, Core Panel, Complete Panel