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Research Article
Finger Length Ratios in Serbian Transsexuals
Svetlana VujoviT,
1
Srdjan PopoviT,
1
Ljiljana MrvoševiT MarojeviT,
1
Miomira IvoviT,
1
Milina TanIiT-GajiT,
1
Miloš StojanoviT,
1
Ljiljana V. Marina,
1
Marija BaraT,
1
Branko BaraT,
1
Milena KovaIeviT,
2
Dragana Duišin,
3
Jasmina BarišiT,
3
Miroslav L. DjordjeviT,
4
and Dragan MiciT
1
1
Clinic for Endocrinology, Diabetes and Metabolic Diseases, Clinical Centre of Serbia, Faculty of Medicine,
University of Belgrade, Dr Suboti
´
ca 13, 11000 Belgrade, Serbia
2
Faculty of Medicine, University of Banja Luka, Bosnia and Herzegovina
3
Clinic for Psychiatry, Clinical Centre of Serbia, Serbia
4
University Childrens Hospital, Tir
ˇ
sova10,11000Belgrade,Serbia
Correspondence should be addressed to Svetlana Vujovi
´
c; vujovics@eunet.rs
Received February ; Accepted April ; Published  May 
Academic Editors: J. Heesakkers and V. Mirone
Copyright ©  Svetlana Vujovi
´
c et al. is is an open access article distributed under the Creative Commons Attribution
License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly
cited.
Atypical prenatal hormone exposure could be a factor in the development of transsexualism. ere is evidence that the nd and
th digit ratio (D : D) associates negatively with prenatal testosterone and positively with estrogens. e aim was to assess the
dierence in D : D between female to male transsexuals (FMT) and male to female transsexuals (MFT) and controls. We examined
 MFT, FMT, and  control males and  control females. Precise measurements were made by X-rays at the ventral surface of
both hands from the basal crease of the digit to the tip using vernier calliper. Control male and female patients had larger D : D
of the right hand when compared to the le hand. Control males le hand ratio was lower than in control females le hand. ere
was no dierence in D : D between MFT and control males. MFT showed similar D : D of the right hand with control women
indicating possible inuencing factor in embryogenesis and consequently nger length changes. FMT showed the lowest D : D
of the le hand when compared to the control males and females. Results of our study go in favour of the biological aetiology of
transsexualism.
1. Introduction
Gender dysphoria is characterized by suering from a
strong, persistent discomfort between biological sex and
experienced-expressed gender, with signicant impairment
in interpersonal, familial, social, professional, and other
important areas of functioning []. Since , when Harry
Benjamin dened transsexualism, many etiological hypothe-
ses were suggested. e cause of transsexualism remains
unclear. e hypothesis that atypical prenatal hormone expo-
surecouldbeafactorinthedevelopmentofthetranssexual-
ism was examined by establishing whether an atypical pattern
of digit length could be one of these manifestations [].
Largest ever study of transsexual genetic, which compared the
length of androgen receptor gene, the gene which is known
to make circulating testosterone less eective, shown longer
androgen receptor gene in male to female (MF) transsexuals.
Less potent testosterone could aect the development of the
brain under masculinization and make it more structurally
similar to female brain (Prince Henry’s Institute). is study
is under criticism of many other scientic groups and require
further examinations.
Sexual orientation in humans may be inuenced by
levels of prenatal sex steroids which canalize neuroendocrine
development. As well, some lines of evidence for sexual-
orientation-related dierences in somatic markers of prenatal
sex hormones support this view [].
Recent attention has been paid to gender specic patterns
of asymmetry in paired bilateral traits. Sexual dimorphism
on digit length ratio is a feature common to many mammals
Hindawi Publishing Corporation
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Volume 2014, Article ID 763563, 4 pages
http://dx.doi.org/10.1155/2014/763563
e Scientic World Journal
[]. Previous studies indicated that the ngers in the adult
humanhanddierinlengthandindistalextentinthe
clear majority of males []. e distal extent of the ring
nger (D) tends to be relatively greater, using the middle
nger as standard, than the index nger (D) in men. So,
men have smaller D : D ratio compared to women. It was
hypothesized that nger length pattern development might
be aected by early androgen exposure. ere is evidence
that the ratio of the length of nd and th digits (D : D)
associates negatively with prenatal testosterone and positively
with prenatal estrogens [].
Duringearlyfetallifethedigitsofthehandsaresimilar
in length. Subsequently, under hormone exposure (pre-
dominantly androgens), dierentiation leads to a pattern
of unequal nger lengths, described by Peters et al. as the
nger-digit length pattern []. e sexual dimorphism is
determined as early as the th week of fetal life []. A
signicant negative association between D : D ratio and
fetal testosterone/fetal estradiol ratio was found in amniotic
uid.esendingslentsupporttoanassociationbetween
low D : D and high levels of free testosterone relative to
free estradiol and high D : D with low free testosterone
relative to free estradiol []. Prenatal androgen appears to be
important in the development of D : D sex dierence, since
ithasbeenreportedinchildrenasyoungasyearsoldand
since human exposed to supernormal androgen level display
a smaller D : D ratio. e common control by the Hox genes
of the dierentiation of both the urogenital system and the
appendicular skeleton has been proposed as an explanation
for the recent nding that uctuating asymmetry and the
D : D are both associated [, ].
e androgen receptor gene contains a domain, which
includes a variable number of CAG sequences and alleles
withlownumberofCAGrepeatsshowhightransactivation
activity when complexed with testosterone. Low number of
CAG repeats and low D : D are both associated with high
spermnumberandprotectionagainstbreastcancer.is
suggests that CAG number and D : D are correlated; that
is, low CAG number and low D : D indicate high activation
of androgen-responsive genes [].
Second and forth digit ratio was also found to be cor-
related with sexual orientation, le hand preference, fetal
growth, Asperger syndrome, sperm count, autism, breast
cancer in women, and myocardial infarction in men [, ].
Such an indirect parameter, as digit-length, can partly
reect hormone milieu during fetal life.
In the last  years Belgrade gender team followed up 
transsexuals. While many previous studies founded higher
incidence of male to female transsexuals, compared to female
to male transsexuals, our study shown the equal number
[]. So, it was interesting to compare the digit length ratio
(D : D) in our country and compare them with the results
from other studies and controls.
e aim of this study was to determine whether adult
sexually dimorphic physical traits (like nger length ratio)
relate to traits that are largely determined in utero, namely,
whether reduced androgenization in utero during fetal devel-
opment inuenced occurrence of female to male transsexuals
(FMT) and reduced androgens in male to female transsexuals
T : Some characteristics of transsexuals.
Characteristics Male to female Female to male
Years of age . ± . . ± .
Weight (kg) . ± . . ± .
Hight (cm) . ± . . ± .
BMI (kg/m
) . ± . . ± .
Age at request (years) . ± . . ± .
Time since operation (years) . ± . . ± .
Mother’s age (years) . ± . . ± .
Father’s age (years) . ± . . ± .
(MFT). In addition, we wanted to assess dierence in D : D
ratio between transsexuals and controls.
2. Subjects and Methods
e tested groups were divided into the following:
(I) male to female transsexuals (MF):  subjects.
(II) female to male transsexuals (FM):  subjects.
Main characteristics of transsexuals are shown in Table .
e diagnosis of gender identity disorder was made by
consensus of two board certied psychiatrists, according to
the criteria of the th edition of the Diagnostic and Standard
Manual of Mental Disorders [].
ey were, otherwise, healthy individuals:
(III) male controls (MC):  subjects,  ± . years of age,
BMI  ± . kg/m
2
.
(IV) female controls (FC):  subjects,  ± . years of age,
BMI . ± . kg/m
2
,withregularmenstrualcycles.
Manning et al. []foundthatD:Dfromphotocopies
tended to be lower than that from direct measurements.
Finger length dierences could result from the shapes of fat
pads at the tips of the ngers and these may be dependent
onsexandsexualorientation.So,wemadethedecisionto
make a more precise measurement of digit lengths by X-
rays at the ventral surface of the both hands from the basal
crease of the digit to the tip using vernier caliper measuring
to . mm, according to the standard published procedure
and recommended guidelines of Bergsma and Feingold [].
is measurement is known to show high degree of repeata-
bility. Intraobserver variability in measurement technique
was .%. All measures were done in transsexuals prior to
hormone reassignment therapy.
At the time of the research the medical authorities in
Serbia did not require approval of the Ethic Committee. Par-
ticipation in the study was voluntary and anonymous.
We have used parametric test (unpaired 𝑡-test, simple
linear and multiple regression test) for all analysis. Means
and standard errors were reported as measures of central
tendency and dispersion. Statistical analysis was performed
with ANOVA, Kruskal-Wallis and Wilcoxon test.
e Scientic World Journal
3. Results
ResultsoftheD:Dratioinmaletofemaletranssexuals,
female to male transsexuals, and control males and females
are shown on Figure .
Our study found larger D : D for right hand in control
males, compared to le hand (. versus .). Control
female exhibited, as well, larger D : D for right hand,
compared to le hand (. versus .). Control males le
hand ratio D : D is lower (.) than in female le hand
control (.) while there were no dierences for the right
hand (. versus .).
No dierences were found between MFT and control
males in D : D (. : .). MFT shown similar D : D
of the right hand with control women (. versus .) indi-
cating some possible etiological factor inuencing period of
embryogenesis and nger length changes. Interestingly, FMT
shownthelowestD:Dratioofthelehandcomparedto
the ratio in control males and females (. versus .
versus .).
4. Discussion
e etiology of transsexualism is not yet claried. Many hyp-
othesis exist and this study shown some more data in exam-
ining some indirect parameters of early androgen exposure
of the sexual dimorphic brain region and changes of nger
length ratio.
From the period when Swaab discovered changes in a
special brain nucleus dierences between male and female
transsexuals and controls attention was paid on all other body
characteristics.
Kallai et al. [] found that the D : D ratio was associ-
ated with and asymmetry in the hippocampal subregion.
Smallervolumeofthelesidewasfoundinposterior
part of the hippocampus in female with a low (masculine
type) D : D ratio. us development of the middle and
posterior regions of the hippocampal formation may respond
in opposite ways to prenatal levels of testosterone. Such a
dierence was not detected in some other brain regions. Our
study conrmed that FMT had the lowest le hand D : D
compared to control males and control females (. versus
. versus .).
Study of Manning et al. []showedthatD:Dinright
and le hands had a sexually dimorphic pattern. ey found
that in males D : D was . meaning that fourth digit
tended to be longer than second while in females the ratio
tended to be . meaning equal length. Our study indicated
the ratio of . in control male le hand, while in control
females le hand it was .. Normative values of male mean
D : D ratio vary between . and . across population [].
We found D : D male ratio (right hand . versus le
hand .). According to Buck et al. study [] the male ratio
D : D was . and female .. Larger sex dierences
were found for the right hand of males indicating that the
right hand D : D is more sensitive to fetal androgens than
thelehandratio[].
Schneider et al. [] found D : D in MFT similar to that
in control female which is consistent with our ndings for the
Right
Hand
Le
0.80
0.85
0.90
0.95
1.00
1.05
1.10
1.15
1.20
1.25
FMT
CF
MFT
CM
F:Fingerlengthpatternsintranssexualsandcontrols.FMT:
female to male transsexuals. CF: control females. MFT: male to
female transsexuals. CM: control males.
right hand (. versus .) conrming lower androgeniza-
tion eects in MFT during embryogenesis.
FMT had the lowest le hand D : D compared to con-
trol females and control males (. versus . versus
.) conrming the hypothesis of androgenization of
femalebrainduringprenatalperiodinFMT.
Peters et al. [] have shown that the sexual dimorphism
inngermeasuresismorestronglyexpressedinthedistal
extent of nger tips than in the length of nger. Smaller
between-nger dierences were found for females than for
males. Lesser distal extent of the index nger, relative to the
middle nger, was found in males than in females.
Nevertheless, Bang et al. [] conrmed that nger length
measurements do not have power to predict the testicular
function in adult men.
Meta-analysis of accumulates evidence of eects of func-
tional androgen receptor gene variants and D : D does not
support initial evidence [].
e present data suggest an early organizational eect of
sex hormones through the association between body shape
and nger length patterns. Also, these data draw attention
to diculties in the interpretation of results when somatic
features are employed as biological markers.
5. Conclusion
Transsexualism in humans is biological in origin. Our
ndings support a biological etiology of MFT implicating
decreased prenatal androgen exposure in MFT. D : D could
be potentially used as a marker for prenatal androgen expo-
sure.
Conflict of Interests
e authors declare that there is no conict of interests
regarding the publication of this paper.
e Scientic World Journal
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Hindawi Publishing Corporation
http://www.hindawi.com Volume 2014
Computational and
Mathematical Methods
in Medicine
Ophthalmology
Journal of
Hindawi Publishing Corporation
http://www.hindawi.com Volume 2014
Diabetes Research
Journal of
Hindawi Publishing Corporation
http://www.hindawi.com Volume 2014
Hindawi Publishing Corporation
http://www.hindawi.com Volume 2014
Research and Treatment
AIDS
Hindawi Publishing Corporation
http://www.hindawi.com Volume 2014
Gastroenterology
Research and Practice
Hindawi Publishing Corporation
http://www.hindawi.com Volume 2014
Parkinsons
Disease
Evidence-Based
Complementary and
Alternative Medicine
Volume 2014
Hindawi Publishing Corporation
http://www.hindawi.com