Androgen Receptor Sensitivity & CAG Repeats
Why two men with equal testosterone respond differently
Evidence grade 3 of 5, Mixed. Read how the Atlas grades evidence.
The written rationale for this grade is still being prepared.
- FDA
- Not applicable (physiology)
Reference only. Not medical advice.
This is something to take to a clinician. The Atlas can tell you what is known about androgen receptor sensitivity & cag repeats in general. It cannot tell you what is happening in your body, and the difference matters most for exactly the symptoms that bring people to this page.
Testosterone's effect depends not just on its blood level but on how sensitively the androgen receptor (AR) responds. The AR gene contains a polymorphic CAG-repeat sequence: shorter repeats generally produce a more transcriptionally active receptor (greater androgen sensitivity), longer repeats a less active one. This partly explains why two men with identical testosterone can differ in symptoms, muscle response, and side effects, and why 'optimizing' a number ignores receptor-level variation. It also underlies androgen insensitivity syndromes at the extreme.
The hormone is only half the story, receptor sensitivity is the other half.
What it is invoked to explain
Claims this idea is used to support. Whether it supports them is the rest of the entry.
How it is supposed to work
The AR's N-terminal CAG (polyglutamine) tract modulates its transcriptional activity: shorter tracts increase coactivator recruitment and androgen sensitivity, longer tracts reduce it. Combined with tissue-specific 5-alpha-reductase (DHT amplification) and local cofactors, receptor genotype means the same serum testosterone produces different downstream signaling between individuals, a reason symptoms, not just numbers, should guide evaluation.
What people get wrong
Often saidThe same testosterone level means the same effect in every man
ActuallyAndrogen-receptor CAG-repeat variation and tissue DHT conversion mean identical testosterone levels can produce different effects between men. The receptor matters as much as the hormone.
Who profits, and who pushes back
Nobody is named here yet, because we have not done that work on this entry. Read that as unfinished. Somebody almost certainly sells this, and somebody almost certainly disputes it. Assume both until we have checked.
At a glance
- Gene
- Androgen receptor (X chromosome)
- Variant
- CAG-repeat length
- Effect
- Shorter repeats -> more sensitive receptor
What this entry does not yet cover
What follows is unfinished work on our side, not a finding about Androgen Receptor Sensitivity & CAG Repeats. A short entry is not a safe entry.
- Timeline. We have not built the dated record of research and regulatory events.
- Cost and market. We have not documented what it sells for or who sells it.
- Supply chain. We have not mapped where it is made.
- Who uses it. We have not documented the user groups.
- What could change. No forward-looking summary yet.
- How it compares. We have not set it against the alternatives.
- Children and teenagers. We have not checked what is known about younger people.
- What can go wrong. We have not written the risk line for this one. Read the safety section below rather than treating its absence as reassurance.
- Where we land. We have not taken a position on this yet.
Sources
No sources recorded for this entry yet. Nothing on this page can be checked against a citation until that changes, so treat it as a summary awaiting its evidence.