Contribution of androgen receptor sensitivity to the relation between testosterone and sexual desire: An exploration in male-to-female transsexuals.
BACKGROUND
Low sexual desire is present in 1/3 of male-to-female transsexuals (post-operative male-to-female transsexual persons on estrogen replacement). Several studies report lower endogenous testosterone (T) levels in this group compared to community dwelling women. However, no relationship between T and sexual desire has been found in male-to-female transsexuals. Considering its role in androgen sensitivity, cytosine-adenine-guanine (CAG) trinucleotide repeat sequence in the androgen receptor (AR) might modify the relationship between T levels and sexual desire in male-to-female transsexuals.


OBJECTIVE
This study aims to assess the potential contribution of the number of CAG repeats in the association between T and sexual desire in male-to-female transsexuals. MATERIAL, SUBJECTS, AND METHODS: Thirty-four post-operative male-to-female transsexuals participated in a cross-sectional study. The Sexual Desire Inventory, a questionnaire measuring sexual desire, was completed. Serum levels of total (TT) and free T (FT), DHEA-S, SHBG, and LH were measured in morning blood samples. AR gene CAG repeat length was determined by automated DNA fragment analysis of exon 1 of the AR gene.


RESULTS
The CAG repeat length ranged from 14 to 28 with a median of 21. CAG polymorphism was correlated with FT (r=0.389; p=0.023) but not with TT (r=0.191; p=0.280). The observed interaction between TT and CAG was significant only for solitary sexual desire (p=0.002). The interaction of CAG repeats and FT on sexual desire failed to reach significance.


CONCLUSIONS
We could not establish that CAG repeat length is a consistent modulating factor in the relationship between TT or FT and sexual desire in male-to-female transsexuals.
Elaut
E
E
Department of Sexology and Gender Problems, Ghent University Hospital, De Pintelaan 185, Ghent, Belgium.
Bogaert
V
V
De Cuypere
G
G
Weyers
S
S
Gijs
L
L
Kaufman
J-M
JM
T'Sjoen
G
G
D000368:Aged; D003430:Cross-Sectional Studies; D019314:Dehydroepiandrosterone Sulfate / Q000097:blood; D005260:Female; D006801:Humans; D007989:Libido / Q000502:physiology; D008297:Male; D008875:Middle Aged; D011944:Receptors, Androgen / Q000235:genetics* / Q000502:physiology; D012738:Sex Hormone-Binding Globulin / Q000032:analysis; D013739:Testosterone / Q000097:blood*; D014189:Transsexualism / Q000097:blood* / Q000503:physiopathology* / Q000523:psychology / Q000601:surgery; D018911:Trinucleotide Repeats
C410798:AR protein, human; D011944:Receptors, Androgen; D012738:Sex Hormone-Binding Globulin; D013739:Testosterone; D019314:Dehydroepiandrosterone Sulfate