5[alpha]-reductase type 2 gene variant associations with prostate cancer risk, circulating hormone levels and androgenetic alopecia
Int. J. Cancer: 120, 776–780 (2006)' 2006 Wiley-Liss, Inc.
5a-Reductase type 2 gene variant associations with prostate cancerrisk, circulating hormone levels and androgenetic alopecia
Vanessa M. Hayes1,2*#, Gianluca Severi3,4*, Emma J.D. Padilla1, Howard A. Morris5, Wayne D. Tilley5,6,Melissa C. Southey7,8, Dallas R. English3,4, Robert L. Sutherland1,2, John L. Hopper4, Peter Boyle8 and Graham G. Giles3,41Cancer Research Program, Garvan Institute of Medical Research, St Vincent's Hospital, Sydney, Australia
2University of New South Wales, Sydney, Australia
3Cancer Epidemiology Centre, Cancer Council of Victoria, Melbourne, Australia
4Centre for Molecular, Environmental, Genetic and Analytic Epidemiology, University of Melbourne, Melbourne, Australia
5Hanson Institute, Adelaide, Australia
6Dame Roma Mitchell Cancer Research Laboratories, University of Adelaide, Adelaide, Australia
7Department of Pathology, University of Melbourne, Melbourne, Australia
8International Agency for Research on Cancer, Lyon, France
Controversy exists over the signiﬁcance of associations between
cancer risk and male patterned balding. However, only one pro-
the SRD5A2 (5a-reductase type 2) polymorphisms, A49T and
spective epidemiological study has been able to demonstrate such
V89L, and risk of prostate cancer. These potentially functional
an association.7 Two recent studies have challenged this hypothe-
polymorphisms may alter life-long exposure to androgens with
sis, reporting an association between increased risk of aggressive
subsequent effects on male health and aging. The aim of this study
prostate cancer and reduced circulating levels of testosterone.8,9 In
was to examine the association of these variants with prostate can-cer risk, plasma hormone levels and androgenetic alopecia. Sub-
addition, we have argued that the observed increase in prostate
jects include 827 cases and 736 controls from an Australian popu-
cancer incidence with increased age may be related to the andro-
lation-based case–control study of prostate cancer. Information on
cline age associated decreasing levels of androgens.9
prostate cancer risk factors and patterns of balding were col-
SRD5A2, is encoded by the SRD5A2 gene located at band p23 on
lected. Plasma levels of testosterone, 3a-diol glucuronide (3a-
chromosome 2.10 Two single nucleotide polymorphisms (SNPs)
diolG), dehydroepiandrosterone sulfate, androstenedione, sex hor-
identiﬁed within the coding region of SRD5A2, rs9282858 (G>A)
mone-binding globulin and estradiol were measured for controls.
No associations with the V89L polymorphism were found. Car-
and rs523349 (G>C), have been implicated in inﬂuencing prostate
riers of the rarer A49T A allele were at a 60% higher risk of pros-
cancer risk via altering androgen levels. The alanine to threonine
tate cancer (OR 5 1.60; 95% CI 1.09–2.36; p 5 0.02) and 50%
amino acid change at codon 49 (A49T, GCC to ACC) increases 5a-
lower risk of vertex and frontal balding (p 5 0.03) compared with
reductase activity 5-fold in vitro,11 while the valine to leucine sub-
men homozygous for the more common G allele. Although we
stitution at codon 89 (V89L, GTA to CTA) results in an almost
found little evidence of association between this variant and
30% reduction in enzyme activity both in vitro and in vivo.12 The
plasma levels of 5 measured androgens, circulating 3a-diolG levels
commonly used amino acid substitution nomenclature, A49T and
were 34% lower in A49T A allele carriers (p < 0.0001). Our study
V89L, will be used to identify these genetic markers in this study.
provides evidence that the SRD5A2 A49T A variant is associated
with an increased risk of prostate cancer, lower levels of circulat-
Molecular epidemiological studies of these dimorphic markers
ing 3a-diolG and decreased risk of baldness. These ﬁndings raise
have reported inconsistent ﬁndings with respect to their role in
important questions with respect to previous assumptions con-
prostate cancer risk and/or clinicopathological behavior. A meta-
cerning hormonal inﬂuences on prostate cancer risk in ageing
analysis has reported a modest effect of the A49T polymorphism
on prostate cancer risk, but no role for V89L.13 Reports of associa-
2006 Wiley-Liss, Inc.
tions between the A49T and V89L polymorphisms and plasmaandrogen levels, including testosterone and 3a-diolG, have been
Key words: SRD5A2;
limited.14–17 A single study has reported a null association between
population-based case-control study; plasma androgens; androgenetic
the V89L variant and balding patterns in European men.18
To further examine associations between these two well-deﬁned
polymorphisms and prostate cancer risk, plasma hormone levels
Membrane-bound 5a-reductase type 2 (SRD5A2) is responsible
for the irreversible conversion of testosterone into its more activemetabolite, dihydrotestosterone (DHT) and is essential for the nor-
Abbreviations: 3a-diolG, 3a-diol glucuronide; 3b-diolG, 3b-diol glucu-
mal growth and development of the prostate gland.1 This hor-
ronide; CI, conﬁdence interval; DHEAS, dehydroepiandrosterone-sulfate;
mone-regulator has been implicated in male pathophysiology,
DHT, dihydrotestosterone; E2, estradiol; H–N, Hamilton–Norwood; H–W,Hardy–Weinberg; LD, linkage disequilibrium; OR, odds ratio; RFPC, Risk
including prostate cancer and balding (androgenetic alopecia).
Factors for Prostate Cancer; SRD5A1, 5a-reductase type 1; SRD5A2, 5a-
The ratio of DHT to testosterone has been reported to be highest
reductase type 2; SHBG, sex hormone-binding globulin.
for African–Americans, intermediate for Europeans and lowest for
Grant sponsors: National Health and Medical Research Council (grant
Asian–Americans, which corresponds to reported ethnic-based
numbers: 251533, 940394, 991129, 299955, 396407); Cancer Institute of
risk of prostate cancer for these groups, suggesting an association
New South Wales; Tattersall Family Foundation; Whitten Foundation;
with prostate cancer risk.2 Prostate cancer risk has been associated
Armati Family Foundation, Australia; and BNP Paribas Foundation, Aus-tralia and France. Infrastructure was provided by the Australian Cancer
with vertex pattern balding.3 Increased levels of DHT have been
Research Foundation Unit for the Molecular Genetics of Cancer and The
demonstrated in the male balding scalp,4 while lack of balding is
Cancer Council Victoria.
seen in pseudohermaphrodites (men with congenital 5a reductase
*These authors contributed equally to the manuscript.
deﬁciency) with a concomitant reduced ability to convert testos-
Correspondence to: Cancer Research Program, Garvan Institute of
terone to DHT.5 DHT in turn is metabolized to 5a-androstane-3a-
Medical Research, 384 Victoria Street, Darlinghurst, NSW 2010, Aus-tralia. Fax: 161-2-92958321. E-mail: [email protected]
17b-diol glucuronide (3a-diolG), a predictor of both cutaneous
Received 1 August 2006; Accepted after revision 12 September 2006
and intraprostatic serum 5a-reductase levels.6 These observations
support the ‘‘androgen hypothesis'' that increases in active andro-
Published online 29 November 2006 in Wiley InterScience (www.interscience.
gens (and their metabolites) are associated with increased prostate
Publication of the International Union Against Cancer
SRD5A2 SNPS, PROSTATE CANCER, SERUM ANDROGENS AND BALDING
and androgenetic alopecia, we genotyped the A49T and V89L var-
the Sequenom MassARRAYTM Compact system (Sequenom, San
iants in a large population-based case–control study of Australian
Diego, CA), using matrix-assisted laser desorption/ionization
men (827 cases, 736 controls).
time-of-ﬂight (MALDI-TOF) mass spectrometry. PCR and exten-sion primer sequences were designed using Sequenom RealSNP(www.RealSNP.com). PCR was performed in duplex in 384-well
Subject and methods
plates with a ﬁnal volume of 5 ll containing 2.5 ng of DNA, 103
Qiagen HotStar Taq PCR buffer, 25 mM MgCl2, 25 mM dNTPs,
Subjects were participants in the Melbourne and Perth arms of
200 nM of each of the 4 PCR primers (primer sequences available
the Risk Factors for Prostate Cancer (RFPC) study, an Australian
upon request) and 0.15 U Qiagen HotStar Taq Polymerase. PCR
population-based case–control study of prostate cancer conducted
cycling was executed using an Eppendorf Mastercycler, under the
between 1994 and 1998 and described in detail elsewhere.19,20 The
following conditions: 95°C for 15 min, 45 cycles of 95°C for 20
study focus was the prevention of prostate cancers likely to contrib-
sec, 56°C for 30 sec and 72°C for 1 min, followed by a ﬁnal exten-
ute to premature mortality and, consequently, recruitment was re-
sion step of 3 min at 72°C. The MassEXTEND reaction was per-
stricted to men with tumors diagnosed at an early age and of more
formed using the 13 ACT termination mix (ddATP, ddCTP,
aggressive histopathology. To this end, tumors that were well-dif-
ddTTP, dGTP), 600 nM of each extension primer (primer sequen-
ferentiated and those with Gleason scores less than 5 were
ces available upon request) and 0.063 U of Thermosequenase. The
excluded. Eligible cases with histopathologically-conﬁrmed adeno-
cycling conditions were as follows: 94°C for 2 min, 40 cycles of
carcinoma of the prostate diagnosed before age 70 years were
94°C for 5 sec, 52°C for 5 sec and 72°C for 5 sec. To assess reli-
ascertained from the Cancer Registries of Victoria and Western
ability of the genotyping, 31% of the study samples were ran-
Australia. Random samples of 100%, 50% and 25%, respectively,
domly regenotyped for both A49T and V89L with a concordance
of the cases diagnosed in the age groups younger than 60 years, 60–
rate of 100% and 99.4%, respectively.
64 years and 65–69 years were asked to participate in the study. Eli-gible controls were randomly selected from males on the StateElectoral Rolls (registration to vote is compulsory for adult Austra-
lian citizens) and were frequency-matched to the expected age dis-
Estimates of allele/genotype frequencies and tests of deviation
tribution of the prostate cancer cases in a ratio of 1 control per case.
from Hardy–Weinberg (H–W) equilibrium were carried out using
A total of 1,047 cases and 1,058 controls participated in the study
standard procedures based on asymptotic likelihood theory.23
(65% and 50%, respectively, of those eligible).3 A face-to-face
Linkage disequilibrium (LD) between the 2 variants was assessed
interview was conducted using structured questionnaires to obtain
by using Lewontin's D0, and tests for signiﬁcance were based on
information on potential risk factors including age, history of pros-
asymptotic likelihood theory.24 Fisher's exact test was used to test
tate cancer in ﬁrst-degree relatives, country of birth, life-style
for independence between the SNPs and categorized risk factors,
(including diet) and other potential risk factors for prostate cancer.
namely, age (<55, 55–64, 65–69), country of birth (Australia,
The interviewer also scored the subject's androgenetic alopecia
others), family history of prostate cancer (affected ﬁrst-degree rel-
according to an adapted Hamilton–Norwood (H–N) scale,21 as no
atives, no affected relatives) and tumor stage (stage I to IV) and
balding (H–N stages I and II), frontal balding (H–N stages II, III,
grade (moderate and high). Tests for association between geno-
IIIa and IVa), vertex balding (H–N stage III vertex-V) and frontal
types and the various outcome of interest (i.e., prostate cancer
baldness concurrent with vertex baldness (H–N stage IV, V, Va, VI
risk, circulating hormone levels and androgenetic alopecia) were
and VII).3 Tumor stage (stage I to IV according to the American
performed under codominant, dominant and recessive models.
Joint Committee on Cancer 2002) and grade (moderate, Gleason 5–
Case–control analyses were conducted using unconditional logis-
7 or moderately differentiated; high, Gleason 8–10 or poorly differ-
tic regression and odds ratio (OR) estimates and their 95% conﬁ-
entiated) was recorded from histopathology reports. Informed con-
dence intervals (CI) were derived under likelihood theory.25
sent was obtained from all study participants. Blood samples were
Adjustment for country of birth, age, history of smoking, history
available from 831 cases (79% of participants) and 738 controls
of prostate cancer in ﬁrst-degree relatives (family history), body
(70%). A detailed description of participant characteristics has
mass index (BMI) and alcohol consumption did not materially
been published.22 The study was approved by the Human Research
change the OR estimates from the logistic models. Polytomous
Ethics Committee of the Cancer Council of Victoria (HREC 9500).
logistic regression models were used to estimate ORs by tumorstage (dependent variable with 3 categories: 0, 1 and 2 for con-
Plasma hormone levels
trols, stage I–II and stage III–IV tumors, respectively) and grade
Plasma samples of controls only were sent to the laboratory of
(dependent variable with 3 categories: 0, 1 and 2 for controls,
one of us (HAM) in randomly assigned batches of around 80 sam-
moderate-grade and high-grade tumors, respectively).
ples each. The laboratory was blinded to the status of the samples
As plasma levels of testosterone, 3a-diolG, DHEAS, androstene-
(genotype). One scientist performed all measurements with 10%
dione, SHBG and E2 were skewed, linear regression of the trans-
sample pooling per batch for quality control purposes. Plasma
formed levels to test the possible association with genotypes was
dehydroepiandrosterone-sulfate (DHEAS) and sex hormone-bind-
used. Levels of 3a-diolG and E2 were log-10 transformed, while
ing globulin (SHBG) levels were measured using a competitive
the others were square-root transformed. The linear regression mod-
immunometric assay (IMMULITE analyzer, DPC, CA). The inter-
els were adjusted for age and laboratory assay and were ﬁtted using
assay coefﬁcient of variation (CV) was 12.4% at 2.1 lmol/l for
all the controls. Results are presented as adjusted back-transformed
DHEAS and 6% at 26 nmol/l for SHBG. Testosterone and estra-
means and their corresponding 95% CI derived from the ﬁtted
diol (E2) levels were measured using electrochemiluminescence
regression models. These statistical analyses were performed using
immunoassay (Elecsys 2010 analyzer, Roche Diagnostics GmbH,
Stata/SE 8.2 (Stata Corporation, College Station, TX).
Mannheim, Germany). The CV was 1.6% at 36 nmol/l for testos-
The association between genotype and androgenetic alopecia
terone and 11.1% at 93 pmol/l for E2. Plasma androstenedione
was tested using a maximum-likelihood multinomial (polytomous)
and 3a-diolG levels were measured using a radioimmunoassay
logistic regression model (mlogit function in Stata/SE 8.2). The
(DSL-4200 and DSL-6000 respectively, TX). The CV was 10.7%
model, with alopecia as outcome, was ﬁtted adjusting for age and
at 3.3 nmol/l for A and 4.3% at 21.1 nmol/l for 3a-diolG.
including an indicator variable to adjust for the case/control status,because we previously found in this study an association between
alopecia and prostate cancer.3 Finally, an interaction term was
Genomic DNA was extracted from whole blood and genotyped
added to test whether the effect of genotype in cases differed from
in a blinded manner for the A49T (rs9282858) and V89L
the effect in controls. Two separate models were ﬁtted for the 2
(rs523349) SRD5A2 variants. Genotyping was performed using
HAYES ET AL.
TABLE I – SRD5A2 GENE POLYMORPHISMS IN CONTROLS
II). Circulating levels of 3a-diolG for carriers of the GA genotype
AND PROSTATE CANCER CASES
(adjusted mean 5 9.2 nmol/l) were 34% lower than for carriers of
the GG genotype (14.0 nmol/l, p < 0.0001). Similarly, DHEAS
levels for carriers of the GA genotype (2.17 lmol/l) were lower
than for carriers of the GG genotype (2.61 lmol/l), but the differ-
ence was only marginally signiﬁcant (p 5 0.05). We found no evi-
dence of association between V89L and the levels of any analyte
measured (all p 0.1).
For A49T the model including the interaction between genotype
and case–control status showed that the ORs for baldness in con-
trols were lower than the corresponding ORs for cases. The ORs
Number of subjects with at least one of the two variants measured.
for vertex baldness and for vertex and frontal baldness combined
–2Odds ratios and 95% conﬁdence intervals from unconditional logis-
were signiﬁcantly lower than one for controls but not for cases.
tic regression analysis.–3Test for association between genotype andprostate cancer risk (likelihood ratio test).
However, the statistical evidence of an interaction between A49Tand case/control status was only marginal (p 5 0.03) and there isno obvious reason why the association between genotype and
The likelihood ratio test was used to test nested hypotheses and
baldness would be dependent on case/control status. In Table III,
the Wald test to assess statistical signiﬁcance of individual param-
we present the ORs for cases and controls combined. We found
eters. All tests were two-sided. Following convention, nominal
marginal evidence of an association between A49T and alopecia
statistical signiﬁcance was based on p < 0.05. No attempt was
(p 5 0.04) with carriers of the GA allele being at lower risk of ver-
made to adjust for multiple comparisons.
tex baldness (OR 0.56, 95% CI 0.31–1.01) and vertex and frontal
baldness (OR 0.52, 95% CI 0.29–0.94).
Although we found little evidence of an overall association
Genotyping of both A49T and V89L variants was successful in
between V89L and alopecia (p 5 0.1 and 0.3 from the codominant
over 99% of the samples yielding 827 cases and 736 controls with
and recessive models, respectively), the ORs associated with the
at least 1 of the 2 variants determined (826 cases and 734 controls
CC genotype compared with the GG genotype were all higher
with both variants determined, Table I). Only 5 cases (<1%) and
than 1 and were statistically signiﬁcant for vertex baldness (OR
7 controls (1%) were not European in origin, with the great ma-
1.92, 95% CI 1.04–3.54) and vertex and frontal baldness com-
jority of subjects (98.5%) being born in Australia, the British Isles,
bined (OR 1.98, 95% CI 1.08–3.64). We did not ﬁnd statistical
or Western Europe. Median age at diagnosis for the cases was 62
evidence of different ORs between cases and controls (P for inter-
years. The proportion of cases that were diagnosed at age <55,
action between V89L and case/control status 5 0.05).
55–64 and 65–69 was 14% (n 5 113), 52% (n 5 435) and 34%(n 5 279), respectively. Two hundred and ﬁfty-four cases (31%)had a stage III or stage IV tumor and 223 (27%) were poorly dif-
ferentiated or had a Gleason score 8 or higher.
Our study suggests that carriers of the SRD5A2 A49T variant
The distribution of the genotypes was consistent with H–W
have a 34% lower circulating level of 3a-diolG, a 60% higher risk
equilibrium for both loci in cases and controls, and for cases and
of developing prostate cancer and a 50% lower risk of alopecia
controls combined (all p > 0.2). The 2 loci were in strong LD and
than men homozygous for the more common variant. We found
D0 was 0.74 for controls (p 5 0.001), 0.99 for cases (p < 0.0001)
no association between V89L and risk of prostate cancer, baldness
and 0.92 for cases and controls combined (p < 0.0001). There was
or circulating hormone levels.
no association between either genotype and age, or country of
Strengths of our study include its large sample size and detailed
birth or family history of prostate cancer (all p > 0.05).
data on tumor stage and grade and risk factors for prostate cancerincluding the direct assessment of the baldness status of partici-
Prostate cancer risk
pants. Another strength of our study is the evaluation of hormone
The frequency of the A allele in A49T (G > A) was 4.5% for
levels in controls to test whether the genetic variants in SRD5A2
cases and 2.9% for controls, with no subjects homozygous AA
modulate circulating hormone levels, thus facilitating interpreta-
(Table I). The proportion of carriers of the GA genotype was
tion of associations between the SRD5A2 gene variants and risk of
slightly higher in cases (9%) than for controls (6%, p 5 0.02) and
prostate cancer, and androgenetic alopecia. A major limitation of
the corresponding OR was 1.60 (95% CI 1.09–2.36). The propor-
our study is its retrospective nature (case–control design) preclud-
tion of GA carriers was similar for stage I–II (47/569, 8%) and
ing meaningful testing of associations between circulating hor-
stage III–IV (28/254, 11%) tumors (p 5 0.2; OR 1.38, 95% CI
mone levels and prostate cancer.
0.84–2.25). There was no difference in the genotype distribution
Although a meta-analysis,13 and a large (n 5 2,216) multiethnic
by tumor grade, with the portion of GA carriers being similar for
population case-control study,26 failed to support an increased risk
both moderate 56/604 (9%) and high 19/223 (8.5%) Gleason
conferred by the V89L polymorphism, studies since 2003 continue
grades (p 5 0.7; OR 0.91, 95% CI 0.53–1.57).
to report associations between this variant and prostate cancer risk
The frequency of the C allele in V89L (G>C) was 31% for both
in European populations.27–30 In our study, we conﬁrm a lack of
cases and controls (Table I). There was no evidence of association
association between V89L and risk of prostate cancer. The meta-
between genotype and prostate cancer risk as the OR was very
analysis could not exclude the possibility of an association
close to 1 (p 5 0.5). There was no signiﬁcant difference in the fre-
between the A49T polymorphism and risk of prostate cancer, as
quency of the C allele (both 31%) or genotype distribution for tu-
conﬁrmed in our study.13 The discrepancies between studies may
mor stage I–II (8% CC, 45% GC) versus stage III–IV (10% CC,
be due to the relatively low frequency of the A49T risk allele in
41% GC) or for moderate (8% CC, 45% GC) versus high (12%
European populations (3% allele frequency/6% genotype fre-
CC, 39% GC) tumor grade (both p > 0.1).
quency, controls); thus, many small studies will have lackedadequate statistical power to address this question.
The effect of these polymorphic markers on prostate cancer
There was no association between the A49T variant and levels
incidence and clinicopathological behavior has been investigated.
of testosterone, androstenedione, SHBG or E2 (all p 0.18, Table
An increase in the risk of more aggressive disease27 and metastatic
SRD5A2 SNPS, PROSTATE CANCER, SERUM ANDROGENS AND BALDING
TABLE II – HORMONE LEVELS1 BY GENOTYPE IN THE CONTROLS OF THE RFPC STUDY
1Adjusted back-transformed means and their corresponding 95% CI derived from linear regression of the transformed levels. Levels of 3a-
diol G and E2 were log 10 transformed, while the others were square-root transformed. The models were adjusted for age and laboratory assay.
–2Two had missing genotype for A49T.–3Likelihood ratio test for association between genotype and circulating hormone levels. Abbreviations:T, testosterone; 3a-diolG, 3a-diol glucuronide; DHEAS, dehydroepiandrosterone-sulfate; A, androstenedione; SHBG, sex hormone-binding
globulin; E2, estradiol.
TABLE III – SRD5A2 POLYMORPHISMS AND ANDROGENETIC ALOPECIA
No balding (n 5 278)
Frontal (n 5 516)
Frontal and vertex (n 5 389)
OR (95% CI) GC vs. GG
OR (95% CI) CC vs. GG
OR (95% CI) any C vs. GG
1Test for association between genotype and baldness status (i.e., the three ORs for the different baldness categories are all 1); the likelihood
ratio test was used.–2ORs are from a generalized logit model ﬁtted through a log-linear model for multiway contingency tables. Two separatemodels were ﬁtted for the two variants. The models were adjusted for age and case–control status because the prevalence of vertex baldness incases was slightly higher than in controls (p 5 0.04).–3Test for association between genotype and the speciﬁc category of baldness (i.e., both
ORs for GC and CC are 1).
disease,31 for patients carrying the V89L C allele or CC genotype,
sis that high levels of androgens would be associated with an
respectively, and a trend for more advanced stage disease for
increase in prostate cancer risk. In contrast, we found an associa-
patients carrying the A49T A allele (GA genotype)11,31,32 has
tion between the SRD5A2 A49T variant and decreased 3a-diolG
been reported. In agreement with other studies, we found no asso-
levels, as well as increased prostate cancer risk. More recently, 2
ciation between either tumor stage or grade and the V89L or
large prospective studies have shown that high circulating levels
of androgens decrease the risk of aggressive prostate cancer.8,9
It has been suggested that genetic polymorphisms of SRD5A2
The involvement of androgens in androgenetic alopecia is well
mediate their effects via changes in androgen levels, including 3a-
accepted, implicating hormone regulatory genes in predisposing
diolG, a major metabolite of DHT synthesized in the prostate. As
men to this predominantly male condition.36 In addition, a moder-
DHT is largely derived from the SRD5A2 isoform SRD5A1 activity
ate association between prostate cancer and vertex type baldness
in the skin, circulating 3a-diolG concentration is believed to be a
compared with no balding has been described.3 Two independent
more accurate marker of SRD5A2 activity. A study of 604 British
studies have shown an association between the presence of a non-
men participating in the European Prospective Investigation into
functional androgen receptor (AR) polymorphism (AR-E211
Cancer and Nutrition (EPIC) study showed that V89L was not asso-
G>A) and reduced risk of alopecia,22,37 while no association be-
ciated with serum androgen levels, while carriers of the A49T vari-
tween the SRD5A2 V89L variant has been observed.18 We found
ant had 24% lower serum levels of 3a-diolG than individuals
little evidence of an increased risk of vertex or vertex and frontal
homozygous for the common allele (p 5 0.0003).14,15 This strong
balding combined for carriers of the V89L variant, but we did
association between A49T and levels of 3a-diolG was conﬁrmed in
observe a marginally signiﬁcant association between the presence
our study, in which we measured levels of this DHT metabolite in
of the A49T variant and decreased risk of vertex or vertex plus
plasma. After adjusting for age and assay/batch, levels of 3a-diolG
frontal balding combined. This association with decreased balding
were 34% lower for carriers of the A49T variant than for men
is surprising as balding is usually associated with increased DHT
homozygous for the common variant. The latter ﬁnding is in con-
levels, which in turn is associated with increased SRD5A2 activity
trast with the results from a study that showed that the A49T variant
in the presence of the A49T variant. Our ﬁndings that the A49T
increases the activity of SRD5A2 in vitro.11 However, one cannot
variant is associated with lower 3a-diolG plasma levels and, thus,
exclude the possibility that the rarely studied 3b-diolG, an alternate
decreased DHT (assuming 3a-diolG is a true indicator of circulat-
metabolite of DHT,35 together with other hormones, may not have
ing DHT levels) supports our observed association between A49T
inﬂuenced these ﬁndings thus providing an explanation for the
and decreased balding. Thus, contrary to current understanding,
apparent inconsistency between our results and the in vitro study.
our ﬁndings suggest an alternative functional effect of the A49T
The interpretation of these results in terms of prostate cancer
variant on enzymatic activity. Once again we cannot exclude the
risk is further complicated by the historically prevailing hypothe-
possibility that circulating 3a-diolG plasma levels are not being
HAYES ET AL.
inﬂuenced by the enzymatic activity of SRD5A1 (known to be
questions; including the perceived functional consequences of the
active in the skin), by the hydroxysteroid dehydrogenases which
A49T variant and whether 3a-diolG is a true indicator of circulating
convert DHT and dehydroepiandrosterone to 3a-diolG, or by the
DHT levels. It readdresses issues surrounding limitations of assess-
production of 3b-diolG. The interplay between hormones in the
ing circulating androgens as a true reﬂection of tissue-speciﬁc
skin (i.e., scalp and hair follicles), in the circulation and in the pros-
androgen levels and lends weight to the historically less accepted
tate is not well understood. Thus, further studies are needed to
‘‘androcline hypothesis'' of prostate cancer risk.
investigate whether androgen levels in the circulation are trulymarkers of androgen levels within tissues like the prostate and skin.
In this large population-based, case–control study we conﬁrm
previous observations that the SRD5A2 A49T variant is associatedwith increased prostate cancer risk, as well as a decrease in the cir-
We would like to thank the study participants and the many urolo-
culating hormone 3a-diolG in European men. This is also the ﬁrst
gists, nurses, and histopathologists who kindly facilitated the recruit-
study to suggest an association between this polymorphism and
ment and collection of patient information and pathologist reports.
decreased male patterned balding. These ﬁndings raise a number of
V.M.H. is a Fellow of the Cancer Institute of New South Wales.
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R E G L A M E N T O REGLAMENTO DE CONTROL DE DOPAJE II. Violaciones del reglamento contra el dopaje III. Prueba de dopaje 1. Carga y medios probatorios 2. Métodos para establecer hechos y presunciones IV. Organización de los controles de dopaje 1. Disposiciones administrativas 2. Obligaciones de Clubes y de los jugadores 3. Procedimiento del control de dopaje para las muestras de orina
Human Reproduction, Vol.24, No.3 pp. 602 – 607, 2009 Advanced Access publication on December 17, 2008 ORIGINAL ARTICLE Gynaecology Preoperative work-up for patients withdeeply inﬁltrating endometriosis:transvaginal ultrasonography mustdeﬁnitely be the ﬁrst-line imagingexamination Mathilde Piketty1, Nicolas Chopin1, Bertrand Dousset2,Anne-Elodie Millischer-Bellaische3, Gilles Roseau1, Mahaut Leconte2,Bruno Borghese1,4,5, and Charles Chapron1,4,5,6