Reduced artery diameters in Klinefelter syndromeC. Foresta,* N. Caretta,* P. Palego,* A. Ferlin,* D. Zuccarello,* A. Lenzi and R. Selice*
*Department of Molecular Medicine, Section of Clinical Pathology and Center for Human Reproduction Pathology, University of Padova, Padova,
Italy, and Department of Experimental Medicine, Section of Medical Pathophysiology and Endocrinology, Sapienza University of Rome, Rome,
Klinefelter syndrome (KS) is the most common sex chro-
mosomal disorder, with a prevalence of 1:600 and it is a
frequent form of male hypogonadism and infertility
(Lanfranco et al., 2004; Bojesen et al., 2006). The KS is
characterized by the presence of one or more extra
X-chromosomes; about 80% of cases have 47, XXY karyo-
type, the remaining 20% have higher-grade chromosome
aneuploidies (48, XXXY, 48, XXYY, 49, XXXXY), mosa-
icisms (46, XY 47, XXY) or structurally abnormal Xchromosomes (Lanfranco et al., 2004). The chromosome
aberration arises by maternal or paternal non-disjunction
during meiotic division in germ-cell development, or
rarely in early embryonic mitotic cell divisions (Lanfranco
et al., 2004).
The clinical features of KS commonly include hypergo-
nadotropic hypogonadism, gynecomastia, small testes and
azoospermia (Klinefelter et al., 1942), but Klinefelter syn-
drome may be associated also with an increased risk of
systemic diseases including malignancies, osteoporosis
(Kubler et al., 1992), venous thromboembolism (Camp-
bell & Price, 1981), diabetes and cardiovascular diseases
(CVDs) (Swerdlow et al., 2005; Bojesen & Gravholt,
2011). Various epidemiological studies in relatively large
cohorts of patients with KS described the increased mor-
bidity and mortality in KS. Focusing on CVDs, Bojesen
et al. in 2004 found that KS was associated with a signifi-
cant increase in mortality risk because of various causes,
including circulatory diseases (Hazard ratio: 1.41). Succes-
sively, Swerdlow et al., 2005found in KS a significantly
raised mortality for diseases of the circulatory system, in
artery diameter, brachial FMD, Klinefelter
syndrome, reproductive hormones
Prof. Carlo Foresta, University of Padova,
Department of Histology, Microbiology and
Medical Biotechnologies, Section of Clinical
Pathology and Center for Human
Reproduction Pathology, Via Gabelli 63,
35121 Padova, Italy.
Received 22 December 2011; revised 8
February 2012; accepted 21 February 2012
Various epidemiological studies in relatively large cohorts of patients with
Klinefelter syndrome (KS) described the increased morbidity and mortality in
these subjects. Our aim was to study the structure and function of arteries in
different districts to investigate in these subjects possible alterations. A total of
92 patients having non-mosaic KS, diagnosed in Centre for Human Reproduc-
tion Pathology at the University of Padova, and 50 age-matched healthy male
controls were studied. Klinefelter syndrome subjects and controls evaluation
included complete medical history, physical examination, measurement of con-
centrations of the reproductive hormones, lipidic and glycidic metabolism, AR
function and sensitivity, ultrasound examinations (diameters, carotid intima-
media thickness and brachial flow-mediated dilation) of brachial, common
carotid and common femoral artery and abdominal aorta. Klinefelter syndrome
patients showed significantly reduced artery diameters in all districts evaluated.
On the contrary no statistically significant difference was found in cIMT and
brachial FMD values between KS patients and controls. Furthermore, we found
no statistically significant correlation of artery diameters with reproductive hor-
mones, metabolic parameters, anthropometric measures and weighted CAG
repeats. To our knowledge, this is the first study finding a reduced artery diam-
eter in several districts in KS patients compared with that of normal male
subjects and overlapping to that of female subjects. We have not an explana-
tion for this phenomenon, even if a possible involvement of genes controlling
the development of vascular system might be hypothesized, and further
research is required to verify this hypothesis.
international journal of andrology ISSN 0105-6263
2012 The Authors International Journal of Andrology, 16International Journal of Andrology 2012 European Academy of Andrology 1
particular for pulmonary embolism [Standardized Mortal-
ity Ratio (SMR): 5.7; 95% CI 2.511.3], cerebrovascular
disease (SMR: 2.2; 95% CI 1.63.0), peripheral vascular
disease (SMR: 7.9; 95% CI 2.917.2), subarachnoid haem-
orrhage (SMR: 3.1; 95% CI 1.26.8).
In recent years, a large body of data focused on the
possible role of diverse ultrasound measurements to
detect early signs of endothelial dysfunction, which in
turn has been considered as the primum movens with
respect to the onset and development of CVDs.
Several studies reported the predictive role of carotid
intima-media thickness (cIMT) in cardiovascular (CV)
risk stratification and future CV events (Chambless et al.,
1997; Lorenz et al., 2007) but such relationship is weak
and adds little to CVD prediction by traditional risk fac-
tors (Simon et al., 2010) and remains a topic of debate,
especially in young subjects.
Also flow-mediated dilation (FMD) has been consid-
ered as a predictor of CVD and other CV events, but its
value for risk stratification of CV events is still debatable
and further studies are needed to resolve such controversy
(Peters et al., 2011).
Recently, few reports documented the correlation
between brachial artery diameter (BAD) and CV risk fac-
tors and or CV events in the general population (Yeboahet al., 2007; Holewijn et al., 2009) and has been suggested
a more promising tool in CV risk prediction (Kullo et al.,
2007; Holewijn et al., 2009). On the basis of these recent
findings, considering that subjects affected by KS have an
increased risk of morbidity and mortality for CVD, we
studied the structure and function of arteries (diameter,
IMT and FMD) in different districts to investigate possible
alterations in these subjects and to correlate these mea-
sures with testosterone levels and function of the andro-
gen receptor (AR) CAG length and inactivation status.
Material and methods
Patients and clinical analysis
We studied, in a prospective study, a total of 92 patients
having non-mosaic KS (mean age 31.5 8.7 years; range
1552 years), diagnosed in Centre for Human Reproduc-
tion Pathology at the University of Padova and 50 age-
matched healthy male controls (mean age 30.8 8.2 years;
range 1949 years) from January 2010 to July 2011.
Patients had been referred to our centre for fertility prob-
lems, testicular hypotrophy, or referred to us for clinical
evaluation by other specialists. Healthy controls were
recruited through andrologic primary prevention check up
for fertility, premature ejaculation, erectile dysfunction
and lower urinary tract symptoms. The study was
approved by the Hospital Ethics Committee and each par-
ticipant gave his written informed consent.
All subjects (patients and controls) underwent periph-
eral karyotype analysis, evaluating al least 50 peripheral
blood lymphocyte metaphases. Each men had never
received testosterone substitution at the time of evalua-
Subjects evaluation included complete medical history
(pubertal history, lifestyle, physical activity, smoking, alco-
hol misuse), physical examination [weight, height, body
mass index (BMI), waist circumference, arm span, body
surface area calculated by the DuBois-DuBois formula;
0.007184 height (cm)0.725 weight (kg)0.425, blood pres-sure] measurement of concentrations of the reproductive
hormones (LH, FSH, total testosterone, estradiol), lipidic
and glycidic metabolism (total cholesterol, HDL, triglyce-
rides, fasting glucose). Patients with more than one super-
numerary X chromosome, mosaicisms, or with any
endocrine dysfunction different from hypogonadism and
subjects assuming any drug were excluded from the study.
Blood pressure was measured in fasting conditions,
between 08.00 and 10.00 h, avoiding cigarette smoking
for a minimum of 12 h. Patients and controls reported a
The AR function and sensitivity was studied through
the evaluation of the CAG repeat length and inactivating
status. The AR gene is located on the X chromosome and
therefore in KS is present in double copy. The inactiva-
tion rate of the two X chromosomes, and the effective
CAG repeat value in heterozygous KS men was calculated
as an X-weighted biallelic mean. This analysis was based
on Methylation-Specific PCR (MS-PCR) at the human
AR locus, with primers spanning the (CAG)n polymor-
phism region, as previously described (Kubota et al.,
Blood was collected in the fasting state between 08.00 and
10.00 h. Serum FSH, LH, total testosterone (T) and estra-
diol (E) were evaluated by commercial electrochemilumi-
nescence immunoassay methods (Elecsys 2010; Roche
Diagnostics, Mannheim, Germany). For all parameters the
intra- and interassay coefficient of variation were
multifrequency linear probe. Intra-observer variability was
estimated to be less than 10%. Images were recorded and
measured in telediastole.
The inner to inner wall diameter (first echoic line in
the lumen, respectively, of near and far wall) of the bra-
chial artery was measured 4 cm above the antecubital
region using a dedicated semiautomatic software available
in the ultrasound machine. The arithmetic mean of six
consecutive measurements was considered for statistical
The common carotid and common femoral artery were
measured with the same semiautomatic software and with
same procedure, both in the trait between 2 and 4 cm
before the bifurcation.
Abdominal aorta was measured using a high resolution
multifrequency convex probe 36 MHz: the mean of
three inner to inner wall measurements in the longitudi-
nal plan, from the infrarenal site to the aorto-iliac bifur-
cation, was considered for statistical analysis.
The IMT was measured in longitudinal scan, bilaterally,
in the distal tract, at 30 mm before the bifurcation of
common carotid artery, choosing the most linear tract of
arterial wall as by operators judgement. For each side
three semiautomatic measurements of the far wall IMT,
defined as the distance from the first echoic line between
lumen and wall vessel to the medio-adventitial margin,
were performed and the mean value of these measure-
ments was considered for statistical analysis.
Vascular endothelial function was evaluated with bra-
chial artery FMD (FMD) assessed in the morning, after an
overnight fasting. Longitudinal B-mode ultrasound images
of the brachial artery, 46 cm proximal to the antecubital
crease were taken. Images were obtained after 10 min of
supine relaxation during reactive hyperaemia, which was
induced by inflation for 5 min to suprasystolic pressure
(E20 mmHg) of an occlusion cuff placed around the fore-
arm. Increased blood flow and shear stress during hypera-
emia leads to NO-dependent FMD of the brachial artery.
End-diastolic images were stored and arterial diameters
were measured as the distance between the arterial wall
intimamedia interfaces. The FMD was defined as the
maximum per cent change in arterial diameter from 10 to
120 s postdeflation of the occlusion cuff.
Differences between KS patients and controls were evalu-
ated using unpaired two-sided Students t-test. The same
test was used to evaluate differences between KS group
with hypogonadism and KS group with normal testoster-
one plasma levels. Relationships between continuous vari-
ables were assessed using non-parametric Spearmans qcorrelation test.
The significance level was set to p < 0.05. Variables are
given as mean SD.
Table 1 reports that KS patients had, as expected, signifi-
cantly higher weight, waist circumference, BMI, body sur-
face and gonadotropins with respect to controls and
significantly reduced levels of total testosterone.
Age, height, arm span, estradiol, weighted CAG repeat,
blood pressure, history of smoking and metabolic param-
eters (total and HDL cholesterol, triglycerides, glycaemia)
did not show statistically significant differences between
patients and controls.
Table 2 reports brachial, common carotid, common
femoral artery and abdominal aorta diameters in Klinefel-
ter patients and in controls. KS patients showed signifi-
cantly reduced artery diameters in all districts evaluated.
On the contrary no statistically significant difference was
found in cIMT and brachial FMD values between KS
patients and controls.
We then investigated in Klinefelter patients possible
associations between artery diameters, hormonal, meta-
bolic parameters and anthropometric measures. We found
Table 1 Clinical, metabolic, hormonal parameters and anthropomet-
ric measures in 92 Klinefelter patients compared with 50 controls
(n = 92)
(n = 50) p
Age (years) 31.5 8.7 30.8 8.2 n.s.
Height (cm) 181.5 7.5 179.9 6.1 n.s.
Weight (kg) 84.3 16.8 77.3 12.0
no statistically significant correlation between artery
diameters (brachial, common carotid, common femoral
and abdominal aorta) and reproductive hormones (LH,
FSH, total testosterone, estradiol, LH total T, T E),anthropometric measures (height, weight, BMI, body sur-
face, waist, arm span) and metabolic parameters. Further-
more, we found no statistically significant correlation
between artery diameters and weighted CAG repeats (data
We then subgrouped KS patients in subjects with
reduced total testosterone plasma levels (
24) and the common carotid artery diameter between 5.4
and 5.7 mm (Jensen-Urstad et al., 1999; Ruan et al.,
2009; Dengel et al., 2011), Gonzales et al. report in young
women a diameter for femoral artery of 7.1 mm (Gonz-
ales et al., 2010). Our results showed that KS patients
have a diameter of brachial, common carotid and com-
mon femoral artery overlapping to women despite the
difference in height. Whether this is an effect of the extra
X-chromosome remains unknown, although intriguing. In
our study the height, as the other anthropometric mea-
sures, did not differ between KS patients and controls,
therefore the finding of smaller artery diameters is not
influenced by them.
Recently, few reports documented the correlation of
brachial artery diameter (BAD) with CV risk factors
and or CV events in the general population (Yeboahet al., 2007; Holewijn et al., 2009). Holewijn et al., 2009
showed a negative correlation between BAD and CVD in
337 subjects aged 5070 years enrolled from general pop-
ulation, whereas Yeboah et al., 2007 found that the event-
free survival rate for CV events for subjects with BAD
below or equal to the median was higher than for those
with BAD above the median. Furthermore, Kullo et al.,
2007 studied asymptomatic subjects drawn from the com-
munity (mean age 61 years) finding that greater BAD was
associated with the presence and quantity of coronary
artery calcium, independent from coronary heart disease
risk factors, although this association was weak.
To our knowledge, this is the first study finding in KS
patients a reduced artery diameter in several districts
(brachial, common carotid, common femoral and
abdominal aorta) compared with that of normal male
subjects and overlapping to that of female subjects.
Furthermore, an involvement of hormone imbalance,
anthropometric measures, metabolic parameters, andro-
gen receptor sensitivity as causative for this difference has
We do not have an explanation for this phenomenon,
even if a possible involvement of genes controlling the
development of vascular system might be hypothesized.
Considering that in the opposite condition of KS, Turner
syndrome (45, X) there is a general dilatation of the same
arterial beds (Mortensen et al., 2011), we could hypothe-
size that a gene or genes on the X chromosome and a
possible paralogue on the Y needs to be present in two
copies to control normal growth of arteries, whereas hav-
ing only one gene leads to dilatation, while three copies
leads to insufficient growth. This of course especially
implicates pseudoautosomal genes like for instance the
SHOX gene, which has not so far been implicated in the
growth of arteries, but has BNP as one of its transcrip-
tional targets. Further research is required to verify this
A limitation of our study is the lacking of echocardiog-
raphyc data to correlate our findings with cardiac func-
tion parameters. Recently Andersen et al. (Andersen et al.,
2008) found a higher left ventricular mass index in KS
subjects with respect to controls. This observation sug-
gests a possible increase of peripherical resistance related
to a reduced artery diameters. However, our patients
showed systolic and diastolic blood pressure levels not
statistically significant different with respect to controls,
probably as a consequence of a reduced resistance at
small arterial and arteriolar level.
In conclusion, our study provides new insight into rela-
tions between Klinefelter syndrome and CVD. For the
first time in KS patients we observed a reduced artery
diameter in several districts that should be implicated in
increased CV morbidity and mortality. Further studies are
necessary to clarify the pathogenesis and clinical implica-
tions of our findings.
Conflict of interest
The authors have nothing to disclose.
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International Journal of Andrology, 16 2012 The Authors6 International Journal of Andrology 2012 European Academy of Andrology