Introduction:
Gender Dysphoria (GD) is defined as a marked incongruence between one’s
experienced/expressed gender and assigned gender that the individual
feel a strong desire for having the sex characteristics of the other
gender(1). In the Diagnostic and Statistical Manual of Mental Disorders
(DSM-5), the prevalence for male-to-female gender dysphoria is reported
between 5 and 14 per 1000 adult males and 2 and 3 per 1000 adult females
for female-to-male gender dysphoria(2). Twin review literature on GD
supports the role of genetics in the development of gender identity with
a higher GD concordances in Monozygotic (MZ) (37.5%) versus Dizygotic
(DZ) (0%) twins; however this concordance in MZ (37.5%) twins found to
be less than their discordances (62.5%) among the total of MZ twin
pairs(3). Taking the limited number of twin samples and genetic studies
in GD, more twin studies could be helpful in making decisive conclusion
on the contribution of genetics in GD over environmental factors. In
this study we report a monozygot (MZ) female twins that are concordant
for GD with surprisingly different temperament features.