SHBG gene promoter polymorphisms in men are associated with serum sex hormone-binding globulin, androgen and androgen metabolite levels, and hip bone mineral density.
BACKGROUND
SHBG regulates free sex steroid levels, which in turn regulate skeletal homeostasis. Twin studies have demonstrated that genetic factors largely account for interindividual variation in SHBG levels. Glucuronidated androgen metabolites have been proposed as markers of androgenic activity.


OBJECTIVE
Our objective was to investigate whether polymorphisms in the SHBG gene promoter [(TAAAA)(n) microsatellite and rs1799941 single-nucleotide polymorphism] are associated with serum levels of SHBG, sex steroids, or bone mineral density (BMD) in men.


METHODS
We conducted a population-based study of two cohorts of Swedish men: elderly men (MrOS Sweden; n congruent with 3000; average age, 75.4 yr) and young adult men (GOOD study; n = 1068; average age, 18.9 yr).


METHODS
We measured serum levels of SHBG, testosterone, estradiol, dihydrotestosterone, 5alpha-androstane-3alpha,17beta-diol glucuronides, androsterone glucuronide, and BMD determined by dual-energy x-ray absorptiometry.


RESULTS
In both cohorts, (TAAAA)(n) and rs1799941 genotypes were associated with serum levels of SHBG (P < 0.001), dihydrotestosterone (P < 0.05), and 5alpha-androstane-3alpha,17beta-diol glucuronides (P < 0.05). In the elderly men, they were also associated with testosterone and BMD at all hip bone sites. The genotype associated with high levels of SHBG was also associated with high BMD. Interestingly, male mice overexpressing human SHBG had increased cortical bone mineral content in the femur, suggesting that elevated SHBG levels may cause increased bone mass.


CONCLUSIONS
Our findings demonstrate that polymorphisms in the SHBG promoter predict serum levels of SHBG, androgens, and glucuronidated androgen metabolites, and hip BMD in men.
Eriksson
A L
AL
Center for Bone Research at the Sahlgrenska Academy, Department of Internal Medicine, Division of Endocrinology, Göteborg University, Sweden.
Lorentzon
M
M
Mellström
D
D
Vandenput
L
L
Swanson
C
C
Andersson
N
N
Hammond
G L
GL
Jakobsson
J
J
Rane
A
A
Orwoll
E S
ES
Ljunggren
O
O
Johnell
O
O
Labrie
F
F
Windahl
S H
SH
Ohlsson
C
C
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000728:Androgens / Q000097:blood* / Q000378:metabolism; D000818:Animals; D015519:Bone Density / Q000502:physiology*; D005838:Genotype; D006615:Hip / Q000502:physiology; D006801:Humans; D008297:Male; D051379:Mice; D008822:Mice, Transgenic; D018895:Microsatellite Repeats / Q000502:physiology; D011110:Polymorphism, Genetic; D011401:Promoter Regions, Genetic; D012738:Sex Hormone-Binding Globulin / Q000032:analysis* / Q000235:genetics*
D000728:Androgens; D012738:Sex Hormone-Binding Globulin