Discussion:
We introduced a monozygot (MZ) female twins with normal physical,
mental, hormonal evaluations which were concordant for GD. Within
different severity of GD in each pairs, paradoxical temperaments
features were also detected between them.
It is speculated that the development of gender in accordance with its
anatomical sex in childhood could be directed by children’s temperament
and their dynamic relationship with parents(4). However, the etiology of
GD encompasses complicated biopsychosocial factors; including
congenital adrenal hyperplasia or androgen insensitivity syndrome, utero
exposure to phthalates in plastics and polychlorinated biphenyls,
maternal toxoplasma infection, and in individuals with psychiatric
illnesses or with childhood abuse, neglect, maltreatment, and physical
or sexual abuse is more prevalent. Neuroanatomical links mostly
regarding defects in embryonic development and differentiation in
hypothalamic networks and variations in amygdala connectivity and
hemispheric ratios according to gender have been also found to be
associated with GD. Higher prevalence of GD in monozygotic twins than
dizygotic twins has been an indicator of heritability and familiarity of
GD in genetic studies. Some alleles (CYP17 and CYP17 T-34C) have also
been found to have an association (not causation)(5)(6).
According to multifactorial etiology of GD, alongside genetics other
factors may play role in navigating the gender identity. As a result, GD
in many children do not continue into adolescence and adulthood(7). In
this case, we need to follow the twins to check if this concordance for
GD is going to be consisted and persisted. Then we will be able to
better compare their shared temperament characteristics with GD. There
is not sufficient papers to evaluate GD by genetics and twin studies and
thereby it is not clear the exact contribution of genetics, familial
rearing and environmental factors in the formation of GD. Some other
questions also raises like; is it possible that the idea of having SRS
shaped as a shared belief between them? Could it be a form of
sympathetic reaction that the other pair used to cope situation? How
does their concurrent decision for SRS influence the situation? Is it
going to be more deteriorating or more acceptable for the parents to get
on with? Is this concordance facilitate the pain they have for their
gender identity?
Conclusion: In this study we presented twins having concordance
GD. It could emphasize the genetic role in GD inheritance but when it
came to their different temperaments we assumed this disorder need to be
followed up. On the other hand, concordancy in monozygotc twins is still
questionable for temperament and gender dysphoria. More twin studies in
the future with follow-up will enable us to answer these questions