Intersex: falling outside the norm
Submitted by minh on 22 May 2012
By Nina Notman
For example, they may appear female on the outside but have an internal anatomy more typical of males. Or they may have ambiguous genitalia: a girl may have a noticeably large clitoris, or lack a vaginal opening, or a boy may be born with a noticeably small penis, or with a scrotum that is divided so that it looks more like labia. Furthermore, some children are born with mosaic genetics, so that some of their cells have XX chromosomes and some have XY.
Why? Well, there are many different types of intersex and we don’t fully understand everything yet, but genetics and hormone levels in the mother’s womb during pregnancy are two known influences.
Another common cause of intersex in girls is a hormonal imbalance, where a genetic defect causes the adrenal gland of the fetus to produce very high levels of testosterone and other male hormones. This is called congenital adrenal hyperplasia (CAH). Professor Melissa Hinesw2, who researches the condition at the University of Cambridge in the UK, explains: “The testosterone causes the clitoris to grow larger so it looks somewhere between a clitoris and a penis, and it causes the labia to begin to fuse, so they look somewhere between labia and a scrotum.” This condition is identified at birth and treated, and the children are raised as girls. Treatment involves normalising the hormone levels, often followed by surgery for cosmetic reasons or to correct problems with the urethra and the vaginal opening.
Although there are clinical treatments available for most types of intersex conditions, the matter is fraught with psychological and ethical issues. Eric is one researcher keen to find a better way to manage intersex and its perception in society.
“Parents are extremely stressed over the birth of a baby with ambiguous genitals,” he explains. An eagerness to ‘fix’ the child can lead to genital surgery very early in life – often in the first year. But whether this is the best thing for the child is unclear. As well as feeling that they would not have chosen to have the treatment themselves, children born intersex can have issues with shame and secrecy when they grow up. “A lot of patients I see with intersex conditions were not told what happened to them until very late in their adolescence, and they are often very angry at their family for having shielded them.” Early operations can also have a negative impact on sexual function later in life.
This CAH behaviour research is part of a wider study led by Melissa, into gender development in all children. “Why do girls and boys like different toys? Why do children group together to play with others of the same sex? Why are boys, say, more rough and tumble than girls are?” are just some of the questions she is trying to answer. And comparing play behaviour and maternal hormone levels during pregnancy is her tool of choice.
Male fetuses produce a surge of testosterone between weeks 8 and 24 of pregnancy. This then tapers off, and apart from a small surge after birth, the testosterone levels in boys and girls remain approximately the same until puberty. In a study of 14 000 children, Melissa has found that mothers with higher testosterone levels during pregnancy were more likely to have girls who were more masculine within the normal range, and that mothers with lower testosterone levels were more likely to have girls who were less masculine.
Sex determination in mice
Scientists at the European Molecular Biology Laboratory (EMBL)w4 and the UK’s National Institute for Medical Research have discovered that if the Foxl2 gene located on a non-sex chromosome is turned off, cells in the ovaries of adult female mice turn into cells typically found in testes.
These findings will have wide-ranging implications for reproductive medicine and may be used in the treatment of intersex children.
EMBL is a member of EIROforumw6, the publisher of Science in School.
This article is based on interviews given by Professor Eric Vilain and Professor Melissa Hines to the editors of Science in School, Dr Eleanor Hayes and Dr Marlene Rau. Some material was also taken from Melissa Hines’ lecturew3. The lecture and interviews took place during the conference ‘The Difference between the Sexes – from Biology to Behaviour’, at the European Molecular Biology Laboratory (EMBL) in Heidelberg, Germany.
Jordan BK (2003) Wnt4 overexpression disrupts normal testicular vasculature and inhibits testosterone synthesis by repressing steroidogenic factor 1/β-catenin synergy. Proceedings of the National Academy of Sciences of the United States of America 100(19): 10866–10871.
Uhlenhaut NH et al. (2009) Somatic sex reprogramming of adult ovaries to testes by FOXL2 ablation. Cell 139:6, 1130-1142.
w2 – To learn more about Melissa Hines’ research, see her website at the University of Cambridge.
w3 – Watch a video of Melissa Hines’ talk.
w4 – EMBL is Europe’s leading laboratory for basic research in molecular biology, with its headquarters in Heidelberg, Germany.
w6 – EIROforum is a collaboration between eight of Europe’s largest inter-governmental scientific research organisations, which combine their resources, facilities and expertise to support European science in reaching its full potential. As part of its education and outreach activities, EIROforum publishes Science in School.
To learn more about intersex and its ethical and physiological implications, see the website of the Intersex Society of North America.
The Howard Hughes Medical Institute (HHMI) website offers an interactive online activity to investigate sex and gender within the context of testing female athletes.
Read the transcript of another interview with Eric Vilain on the Anneberg Learner website, which provides resources for school teachers.
If you found this article interesting, you may like to browse the rest of the medicine-related articles in Science in School.
Dr Nina Notman is a science writer and editor. After her PhD in synthetic organic chemistry at the University of Bristol, UK, she started a career in publishing, managing the peer-review process of a number of the UK’s Royal Society of Chemistry journals. She then moved into science journalism, working on the society’s flagship magazine, Chemistry World. In early 2012, Nina left the magazine and went freelance.
Intersex or ambiguous sexual phenotypes are not a common topic for discussion, at school or more generally, as an aura of embarrassment or shame often prohibits any mention of sexual pathology.
This article, based on interviews with two researchers in the field, introduces the reader to this tricky topic in clear language, highlighting some of the scientific and social aspects. I particularly appreciated the consideration of the psychological impact of the intersex condition and of the issues surrounding the treatment and rearing of intersex children.
As described in the article, the status and the management of the intersex condition is a highly controversial issue, so it can be profitably used for classroom discussion, especially with upper secondary-school students. It would be particularly applicable for biology (e.g. human reproduction), or in sex education or citizenship lessons. The discussion could involve many social, cultural, bio-ethical and legal aspects, including sex and gender identity, the rights and obligations of parents of an intersex child, the principle of autonomy of patients about medical treatments, and the social acceptance of intersex persons.
Potential comprehension questions include:
Moreover, the web resources offer not only information and materials suitable for secondary-school students, but also further information about the study and management of intersex conditions.
I recommend this article to science teachers and upper secondary-school students who are keen to understand this commonly hidden condition and motivated to promote a better social acceptance of intersex people.
Giulia Realdon, Italy