Clinical characteristics of patients with gender identity disorder at a
Japanese gender identity disorder clinic
Nobuyuki Okabe, Toshiki Sato, Yosuke Matsumoto, Yumiko Ido,
Seishi Terada⁎, Shigetoshi Kuroda
Department of Neuropsychiatry, Okayama University, Okayama, Japan
Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, 2-5-1 Shikata-cho, Okayama 700-8558, Japan
Received 21 August 2006; received in revised form 13 May 2007; accepted 23 July 2007
The aim of this study was to examine the clinical characteristics of patients with gender identity disorder (GID) at a GID clinic
in Japan. A total of 603 consecutive patients were evaluated at the GID clinic using clinical information and results of physical and
neurological examinations. Using DSM-IV criteria, 579 patients (96.0%) were diagnosed with GID. Four patients were excluded
for transvestic fetishism, eight for homosexuality, five for schizophrenia, three for personality disorders, and four for other
psychiatric disorders. Among the GID patients, 349 (60.3%) were the female-to-male (FTM) type, and 230 (39.7%) were the male-
to-female (MTF) type. Almost all FTM-type GID patients started to feel discomfort with their sex before puberty and were sexually
attracted to females. The proportion of FTM patients who had experienced marriage as a female was very low, and very few had
children. Therefore, FTM-type GID patients seem to be highly homogeneous. On the other hand, various patterns of age at onset
and sexual attraction existed among MTF patients. Among the MTF-type GID patients, 28.3% had married as males and 18.7% had
sired children. Thus, MTF-type GID patients seem to be more heterogeneous.
© 2007 Elsevier Ireland Ltd. All rights reserved.
Keywords: Gender identity disorder; Gender ratio; Frequency; Female-to-male type; Male-to-female type
Gender identity disorder (GID) is characterized by a
strong and persistent identification with the opposite sex
and discomfort with one's own sex (American Psychi-
atric Association, 1994). Compared with many other
psychiatric disorders, GID is rare, with an estimated
worldwide lifetime prevalence of 0.001%–0.002%
(Roberto, 1983) or 0.0019%–0.0024% (Landen et al.,
1996a). The incidence of GID patients in Sweden who
requested sex reassignment therapy was reported to be
0.14/100,000/year (Landen et al., 1996b). Thus, it has
been difficult to establish demographic characteristics,
and reports of large samples are limited. There has been
little systematic research from countries outside of
North America and Western Europe that might be
helpful in identifying the similarities and differences in
the disorder, including its associated features, across
Available online at www.sciencedirect.com
Psychiatry Research 157 (2008) 315–318
⁎Corresponding author. Graduate SchoolofMedicine,Dentistryand
Pharmaceutical Sciences, 2-5-1 Shikata-cho, Okayama 700-8558,
Japan. Tel.: +81 86 235 7242; fax: +81 86 235 7246.
E-mail address: email@example.com (S. Terada).
0165-1781/$ - see front matter © 2007 Elsevier Ireland Ltd. All rights reserved.
cultural groups and nationalities. This is the first report
on GID with a large sample size outside North America
and Western Europe.
A total of 603 consecutive Japanese patients
examined at the outpatient GID Clinic of Okayama
University Hospital between April 1, 1997, and October
31, 2005, were included in this study. All patients were
comprehensively evaluated independently by at least
two senior psychiatrists with a special interest in this
area, and if possible, they were evaluated neuropsycho-
logically by a clinical psychologist. Of 603 patients, 579
fulfilled the criteria for GID according to the Diagnostic
and Statistical Manual of Mental Disorders, 4th edition
All patients underwent a standard psychiatric eval-
uation to exclude major functional psychiatric disorders
such as schizophrenia, mood disorder, and neurosis. The
age at onset of GID was defined as the age at which the
patient's first well-defined discomfort with his or her
sexual identity was perceived. Early-onset GID was
defined as GID with age at onset before graduation from
elementary school (Haraldsen et al., 2003), and late-
onset GID as GID with age at onset after entering junior
high school. All patients were evaluated by physical and
neurological examinations, and screened chromosomal-
ly and endocrinologically. All participants signed an
informed consent form.
The GID Clinic at Okayama University Hospital, the
second oldest GID clinic in Japan, was established in
Okayama in 1997. During the study period, it was the
four departments: psychiatry, urology, gynecology, and
plastic and reconstructive surgery. The services at the
GID Clinic include diagnostic assessment, counseling,
genetic testing, hormonal therapy, plastic surgery, and
coordination of social services resources.
All aspects of the present study were approved
by the Ethical Committee of Okayama University
2.2. Diagnostic assessment
GID was diagnosed according to DSM-IV. All GID
patients included fulfilled criteria A to D in DSM-IV. Of
the 603 patients assessed, 579 patients (96.0%) met the
criteria for GID. Four patients were excluded for
transvestic fetishism, eight for homosexuality, five for
schizophrenia, three for personality disorders, and four
for other psychiatric disorders.
2.3. Statistics (data analysis)
Statistical analysis was conducted using SPSS
12.0J (SPSS Inc., Chicago, IL, USA). Independent
sample t-tests were used for comparison of the age at
first visit to our clinic. Other comparisons between
male-to-female (MTF) and female-to-male (FTM)
groups were performed using the Mann–Whitney's U
test. The significance level was set at Pb0.05, and
a confidence interval of a 95% confidence interval was
From April 1997 to October 2005, 579 GID patients
were diagnosed with GID at the GID Clinic of Okayama
University Hospital. A total of 349 (60.3%) were the
FTM-type, and 230 (39.7%) were the MTF-type. The
mean age at first examination was 26.5±6.1 years for
the FTM-type GID patients, and 32.0±10.2 years for the
MTF-type (Pb0.001; independent sample t-test, t=
Of the 349 FTM-type GID patients, 245 (70.2%) first
felt discomfort with their sexual identity before they
entered elementary school, and almost all FTM-type
GID patients (324/349, 92.8%) started to feel discomfort
with their sexual identity before graduation from
Age at onset
Lower grades of
Upper grades of
aSenior high school, senior high school and thereafter.
bFTM, female-to-male type.
cMTF, male-to-female type comparison of age at onset between FTM and MTF groups: Pb0.001 (Mann–Whitney's U, z=−11.747).
316 N. Okabe et al. / Psychiatry Research 157 (2008) 315–318
elementary school (Table 1). In contrast, only 63 of the
230 (27.4%) MTF-type GID patients first felt discom-
fort with their sexual identity before they entered
elementary school, and about half the FTM-type GID
patients (101/230, 43.9%) started to feel discomfort with
their sexual identity after graduation from elementary
school (Table 1).
At first examination, 212/349 (60.7%) of the FTM-
type GIDpatients and 108/230(47.0%) ofthe MTF-type
GID patients had not undertaken hormonal or surgical
therapy (Table 2). Within the two groups, 36 of 349
(10.3%) FTM GID patients and 33 of 230 (14.3%) MTF
GID patients had already undergone total or partial sex
reassignment surgery (Table 2). Many patients who have
had total sex reassignment surgery come to our clinic to
get a medical certificate to legally register the change.
Among the FTM-type GID patients, almost all
patients (322/349, 92.3%) were sexually attracted to
females (Table 3), whereas several patterns coexisted
among MTF-type GID patients. Namely, they were
attracted to males (92/230, 40.0%), or to females (42/
230, 18.3%), to both (32/230, 13.9%), or to neither (62/
230, 27.0%) at the time of investigation (Table 3).
Among the FTM-type GID patients, almost all
patients had experienced emotional love as a male
(311/349, 89.1%), and had not experienced marriage as
a female (332/349, 95.1%) (Table 4). In contrast, among
the MTF-type GID patients, 65 of 230 (28.3%) patients
had experienced marriage as a male, and 43/230
(18.7%) fathered a child (Table 4).
4.1. Gender ratio
In our study, 349 GID patients (60.3%) were the
FTM-type, and 230 (39.7%) were the MTF-type. Thus,
the ratio of FTM:MTF was 1:0.66. In previous reports in
Western countries, the FTM:MTF ratios were 1:8.7
(Bower, 2001), 1:6.6 (Zucker et al., 1997), 1:5.8
(Cohen-Kettenis et al., 2003), and 1:2.9 (Cohen-
Kettenis et al., 2003). The discrepancy between our
result and previous reports in Western countries is
In Japan, vaginoplasty is relatively widely performed
because the operation is not very difficult, although it is
not covered by health insurance, whereas penis con-
struction is performed at only a few hospitals, including
ours, because the operation requires a high level of
Stage of therapy at first examination
total 320 (55%) 184 (32%) 69 (12%)
212 (61%) 96 (28%) 36 (10%)
88 (38%) 33 (14%)
aFTM, female to male type.
bMTF, male to female type.
cHormonal therapy, hormonal therapy without genital plastic
dSex assignment surgery, including mastectomy and mammoplasty.
To femalesTo malesTo bothc
Comparison of sexual attachment between FTM and MTF groups: Pb0.001 (Mann–Whitney U, z=−16.491).
aFTM, female-to-male type.
bMTF, male-to-female type.
cTo both, to both female and male.
Experience of emotional love or marriage, and presence of partner or
Comparison between FTM and MTF groups; experience of emotional
love: Pb0.001 (Mann–Whitney U, z=−6.189); presence of steady
partner: Pb0.001 (Mann–Whitney U, z=−6.688), experience of
marriage: Pb0.001 (Mann–Whitney U, z=−7.617), existence of
child: Pb0.001 (Mann–Whitney U, z=−6.367).
aFTM, female to male type.
bMTF, male to female type.
cExperience of emotional love, yes/no/unknown.
dPresence of steady partner, yes/no/unknown.
eExperience of marriage, yes/no.
fExistence of child, yes/no.
317 N. Okabe et al. / Psychiatry Research 157 (2008) 315–318
technical skill. Therefore, MTF-type GID patients can
undergo vaginoplasty relatively easily anywhere,
whereas FTM-type GID patients have few options
outside our hospital. We hypothesize that this is the
reason our clinic attracts more FTM-type GID patients
than MTF-type GID patients.
GID is rare, with an estimated worldwide lifetime
prevalence of 0.001%–0.002% (Roberto, 1983). How-
ever, a previous study noted that the prevalence of GID
appears to be higher in The Netherlands, with MTF-type
GID found in about 1 in 12,000 inhabitants, whereas
FTM-type GID is seen in 1 in 30,000 inhabitants
(Bakker et al., 1993).
There are about 40 million people living in western
Japan. At our clinic, a total of 349 FTM-type GID
patients, most of whom came from western Japan,
were seen. Therefore, FTM-type GID patients are
present with a prevalence of at least 0.0009%. This
figure is not far from an estimated lifetime prevalence
4.3. Comparison of FTM and MTF groups
Among FTM patients, almost all started to feel
discomfort with their sexual identity before puberty and
felt sexually attracted to females. Thus, the proportion of
patients who had experienced marriage as a female was
low, and having borne children was rare. Therefore,
FTM patients seem to be highly homogeneous. On the
other hand, various patterns exist among MTF patients
in age at onset and sexual attraction. More than 40% of
the MTF-type GID patients started to feel discomfort
with their sexual identity after puberty, and a third of the
MTF-type GID patients feel sexual attraction to females.
As a result, 28.3% had experienced marriage as a male
and 18.7% had fathered children. Thus, MTF patients
seem to be more heterogeneous.
Previous research in Western countries reported
similar results. MTF-type GID patients were thought
to fall into two groups: primary and secondary (Person
and Ovesey, 1974a,b). The former have GID throughout
the course of their development, but the latter are
effeminate homosexuals and transvestites who develop
GID under stress. Our results are in line with previous
reports in Western countries. The homogeneity of
FTM-type GID patients suggests that the occurrence
of FTM-type GID is determined by congenital factors,
whereas the heterogeneity of MTF-type GID patients
suggests the existence of subgroups.
4.4. Limitation of this study
Some limitations of this study have to be considered.
Firstly,this study isclinic-based rather than a field study,
Therefore, the exact prevalence of GID is unclear.
Secondly, one significant factor affecting the proportion
of each diagnosis in this study may be referral bias
because MTF-type GID patients can obtain vagino-
plasty relatively easily in Japan, whereas the GID Clinic
of Okayama University Hospital is the only facility in
western Japan that can perform FTM surgery. As a
result, general psychiatrists may refer patients with
FTM-type GID patients to our center more often.
We thank Ms. Ogino and Ms. Kataoka for their
skillful assistance in the study. This study is partly
supported by a grant from the Zikei Institute of
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