Homosexuality and transsexualism as a function of chromosomal aberrations − Rakyat Biologi

Some people receive an extra Y chromosome from their father. Because they have the XY chromosome pair, they are genotypic males. Grown up, these XYY individuals look like men, are on the average taller than ordinary XY (and even than XXY) men and are not very intelligent -though they are rarely mentally deficient. They have a male sexual identity, but often have a homosexual orientation. They have diminished fertility. I have even come across a publication describing two cases of male-to-female transsexuals requesting a sex change operation who were XYY karyotypes. Given the rarity of transsexualism, this finding could be more than coincidental. Weakly masculinized sexual identity is not necessarily associated with other androgynous traits. For example, several investigations have shown that XYY men are more irritable, anxious and impulsive, and are less empathetic, than XY control subjects. It has even been thought that because these men are proportionately more often found in penitenciaries, the Y chromosome can be labeled the «crime» chromosome or even the chromosome containing «killer» genes. It is now more generally considered that the tallness and low intelligence of these men suffice to explain their more frequent presence in prison: they are not more intrinsically criminal, they are more sollicited by criminals because they are tall, and they get caught more because of their low intelligence. I disagree slightly with this very current point of view. Of course there is no such thing as an intrinsic disposition toward crime. However, I believe the higher prevalence of this genotype in prisons (which undeniably exists) could very well be caused by more than the above two characteristics. The adaptational difficulties caused by their frequently «atypical» sexual orientation, and especially by their bad tempers could also contribute to higher rates of criminal behavior. The XYY criminals are not more violent than the others, but they more frequently do have personality disorders (beyond the ones involved in criminal behavior).

Another viable gonosomy consists of receiving an extra X chromosome -in addition to the XY pair. This condition is called Klinefelter's syndrome (XXY). These men are typically tall, and not very intelligent -though rarely mentally deficient. They have (on the average) a weakly male identity and weakly heterosexual orientation. Men with Klinefelter syndrome are at risk for infertility.

A vignette on a case with Klinefelter’s syndrome

Mandoki and Sumner presented an interesting case of Klinefelter syndrome in a 1991 issue of the journal Clinical Pediatrics. Case SS had been a psychiatric outpatient for two years. He was aggressive, emotionally immature, socially withdrawn and schizoid. His verbal IQ was 70 (low normal bordering on mental deficiency) and his performance IQ was 80, a profile absolutely typical of Klinefelter syndrome. He was tall and had disproportionately long legs. Though his penis was of normal size (an exceptional finding in Klinefelter’s syndrome), his testes were small. He was glabrous (no body hair), had gynecomastia (female-like breasts), abnormally low testosterone and abnormally high luteinizing and folliculostimulant hormone levels. He received propanolol for his aggressiveness, testosterone replacement therapy via intramuscular injections, suction lipectomy for the gynecomastia, and bilateral orchidectomy with testicular implants. He was placed in a special vocational program. Two years after these multiple clinical interventions, his behavior and subjective well being improved dramatically.

N.B. Anomalies which have been noted in Klinefelter syndrome (not mentioned in this case report) include low energy, passivity, sexual inactivity, low self esteem, hypospadia (opening of the urethral canal along the penis), a female configuration of pubic hair (the patch forming an inverted rather than an upright triangle) and a small head circumference.

Some people fail to receive one of the gonosomes from either of their parents, leaving them with only one X chromosome. These people, who have what is called Turner syndrome, look more like women than men -though they do have a barrel-shaped thorax, thin hips, no breasts, and no uterus. These women are also not very intelligent, but are rarely mentally deficient. They feel strongly like women, and are clearly heterosexually oriented. One interesting question which Turner syndrome brings up is whether what is missing is one of the maternal X chromosome or the paternal Y chromosome. There is no doubt that both occur. Interestingly, the stigmata (abnormalities), and the sexual identity and orientation, seem to be about the same regardless of which chromosome is missing. Finally, I cannot resist mentioning the implications of Turner syndrome as a test for the lyonization hypothesis that I explained in chapter 3: in the absence of a second X chromosome, the lyonization hypotheses predicts that Turner cases should be at risk for X-linked recessive diseases and disorders as frequently as men. This is indeed the case. For example, while 8% of Turner women are color-blind, only .5% of normal women are so affected.

Finally, some genotypic females receive an extra X chromosome (XXX). Grown up, these women are a bit taller than average, feel resolutely female, and have a normal heterosexual disposition. Though their genotype often goes undetected, they have several problems. They have diminished fertility, many have abnormal menstruation and/or reach menopause early. They are slightly at risk for schizophrenia or manic-depressive disorder and mental retardation. About one third of these women are nevertheless perfectly normal in all the above respects. There is a lesson to be drawn from these configurations: genotypic females seem to have a more robust sexual orientation. Even when there is a chromosomal aberration (the XXY, XYY, and XXX patterns are trisomies, and Turner syndrome is a monosomy), those individuals with the female genotype have the species-specific sexual identity and sexual orientation, whereas not all those with the male genotype do.

A vignette on a case of Turner’s syndrome

Case S17 is a 14 year old girl who came to my attention after having been seen in a local hospital neuropsychology service. She has an unambiguous X0 karyotype. In other words, every single cell of her body has only one X chromosome instead of the usual XY or XX pattern. She had poor coordination as a young child, suffered frequently from otitis, had eczema and had renal problems. She started hormone replacement therapy at age 10. Her main problem at school was difficulty in mathematics. She is a secluded, quiet, compliant child who is not much sought out by other children. She showed depressive signs and was anxious at the time of neuropsychological consultation. As is typical in Turner’s syndrome, her verbal IQ was normal and her performance IQ was low-normal, bordering deficiency. She had no attention deficit, normal language abilities, normal memory. However, she did have a selective visuospatial deficit, a finding again typical in Turner’s syndrome. She was heterosexually inclined, though sexually inactive, wished to raise children, and hoped to work as a daycare employee with young children. This child’s only adaptational problem was that parental academic expectations were too high for her ability, and she was suffering from decreasing self-esteem. The clinical neuropsychologist expected a good outcome for this particular case.

N.B. Typical abnormalities in Turner’s syndrome include short chubby stature, scoliosis (curved spine), short palmed neck, barrel-shaped chest, craniosynostosis (prematurely fused cranial plates), micrognathia (receding chin), strabismus (crossed eyes), cardiac, ovarian, uterine, intestinal and renal dysgenesis, hypoplasic (small) fingernails, abnormal dermatoglyphs (finger and hand ridges), and callosal agenesis.

So far, I have reviewed only the aberrations of whole chromosomes. However, major biological gender effects can result from translocation of a single gene. Recall that gender is determined by a single gene, Sry, located on the Y chromosome. This gene can, very rarely, be installed in the wrong place, namely on the homologous position of the X chromosome. This can result in a genetically XY individual who lacks male organs or an XX individual presenting marked masculine qualities. One investigator has become able to produce at will such exemplars in mice with a bit of genetic engineering. He adds a DNA fragment containing Sry to the ova of a female mouse, and obtains male-looking XX offspring. Interestingly though, these chimera are sterile, which strongly suggests that there may in fact be more to maleness and femaleness than the mere Sry trigger.