A network meta-analysis published in 2026 in the International Journal of Transgender Health has analyzed the length of the polymorphic CAG repeat of the androgen receptor (AR) gene in transgender and cisgender populations, one of the most studied genetic hypotheses in gender incongruence.
What the AR CAG repeat is
The androgen receptor is a key protein in the action of testosterone. A repetitive stretch of amino acids (glutamine, encoded by CAG) influences receptor activity: longer lengths are associated with lower transactivation. It has been proposed that this variability could modulate androgen-dependent brain development.
Results of the meta-analysis
The study integrates data from multiple cohorts and compares the distribution of CAG lengths between transgender people and cisgender controls. The results provide evidence on the heritability of gender incongruence and point out the strengths and methodological limitations of candidate gene studies in this field.
The authors conclude that, although there are indications of a genetic contribution, studies with larger samples and independent replication are necessary to establish definitive associations.
Bibliographic reference: Androgen receptor CAG repeat length in transgender and cisgender populations: a network meta-analysis. International Journal of Transgender Health, 2026. DOI: 10.1080/26895269.2025.2609203.
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