Transsexual sisters

Transsexualism in female monozygotic twins: a case report

OBJECTIVE

A case report is presented of a gender identity disorder involving a pair of female monozygotic twins who requested sex reassignment. As far as we know, this case is the first in psychiatric literature and supports a genetic aetiology of this disorder.

CLINICAL PICTURE

The patients were two 18-year-old female monozygotic twins who had showed symptoms of transsexualism since early childhood. They had no other physical or psychiatric disorder except borderline mental functioning.

TREATMENT

The patients were referred for sex reassignment.

OUTCOME

They were lost to follow up after initial evaluation.

CONCLUSION

In addition to other possible (yet not confirmed) causes of transsexualism, a genetic basis for this disorder is suggested by this case.

Role of genetic factors in human sexual behavior based on studies of Tourette syndrome and ADHD probands and their relatives

Most significant variations in the expression of human sexuality are considered to be the result of learned behavior or psychological problems. Tourette syndrome (TS) is a common, hereditary tic and disinhibition disorder sometimes associated with compulsive use of obscene words (coprolalia) and previously reported to be occasionally associated with exhibitionism. To further explore the relationship between the Gts genes and sexual behavior, questions concerning a wide range of such behaviors were administered to 1,040 subjects, 14 years of age or older, consisting of 358 TS probands, 101 non-proband relatives with TS, 359 non-TS first degree relatives, 79 attention deficit hyperactivity disorder (ADHD) probands, 70 unaffected relatives of the ADHD probands, and 73 controls. The behaviors included magnitude of sex drive, sex orientation, exhibitionism, transvestitism, transsexualism, sadism, masochism, pedophilia, fetishism, aversion to being touched, and aversion to sex. While most of these behaviors occurred in a distinct minority of TS subjects, there was a significant positive correlation between each behavior examined and the degree of genetic loading for the Gts gene(s). The nature of these behaviors and their association with TS suggests many are variants of obsessive-compulsive disorder. Studies in animals indicate that changes in serotonin and dopamine play a significant role in the sexual behavior and many lines of evidence are consistent with the hypothesis that TS is due to genetic changes in serotonin and dopamine metabolism. These studies suggest that genetic factors play a much greater role in a wide range of forms of sexual expression than previously thought.