Claire Burrows is seven. A pretty, vibrant, healthy child, she is full of the joy of pre-adolescence and the innocence of youth. But over the next few years she must come to terms with what her parents have not yet told her: although she has the body of a girl, she is genetically a boy.

Margaret, a 43-year-old researcher, had her first affair last year. It was a disaster; 10 months on she is still having therapy. The break-up of a relationship, particularly the first one, is often damaging, but for Margaret it had an extra significance. She too is genetically male and for 30 years had avoided involvements. For Helen, a 33-year-old lecturer, diagnosis of her condition led her into a series of promiscuous relationships in an effort to exert her female sexuality and deny her male genes.

Margaret, Claire and Helen are 'XY females', three out of several hundred women in the UK who were conceived as male but born as female. They have Androgen Insensitivity Syndrome (AIS), also known as Pseudo-Hermaphroditism and Morris's Syndrome, a rare inherited genetic defect. It creates an insensitivity to the key male hormone, androgen, responsible for promoting male physical characteristics. The result is a baby with the chromosomes of a man but the body of a woman. XY women cannot have children.

There are two forms of AIS, complete and partial. Women with the complete form may need reconstructive surgery to make or lengthen the vagina and to create other female genitalia. The women have no ovaries, fallopian tubes or uterus. The vagina may be just a dimple or a short tube.

Until recently XY women have lived in ignorance or kept their secret hidden. Now sufferers want to raise awareness of the condition with the aim of improving medical treatment and counselling. They also want to end what is often a desperate cycle of isolation.

Jackie Burrows, Claire's mother, has founded the AIS Support Group. 'My daughter was diagnosed six years ago. We were absolutely shell-shocked. She is having an operation later this year and will then have females hormone replacement therapy.

'AIS parents and women need help and compassion and counselling. Diagnosis is traumatic. There must be more physchological support, more awareness of AIS to make life easier for a new generation of women like Claire.'

Everyone has two sex chromosomes, one from each parent. In normal XX females, one X comes from the mother, the other from the father. In normal XY males, the Y can only come from the father. The AIS defect is on the X chromosome and comes from the mother. She does not have AIS because only one of her two X chromosomes has the defect, but she has one in four chance of having an AIS daughter.

Sex is decided at the moment of conception, but for the next eight weeks the embryo has the cells necessary for either a male or a female reproductive system. In AIS, the child is conceived as a male with normal XY chromosomes, but the testes form inside the body. They begin to produce the male hormone, androgen. But in AIS embryos there is an inherited insensitivity to the masculinising effects of androgen and the foetus develops as a female but lacking female genital organs.

The condition is often diagnosed in infancy, when the child is treated for a hernia in the groin caused by the primitive undescended testes, or at puberty when there is a failure to menstruate.

One hospital where vaginoplasty and other genital plastic surgery is carried out is St Bartholomew's in London. Hilary Everett, a gynaecology social worker at the hospital, has counselled a number of AIS women. 'AIS patients are anatomically, hormonally, legally and socially female. Great care is needed not to upset their gender identity. It is important that explanations start from the basis that the client is female. With parents, particularly the mother, there is often a guilt feeling, too.'

But these women can suffer harrowing experiences at the hands of the medical profession, paraded as fascinating cases and quizzed about their sexuality and gender. 'I was introduced to medical students and junior doctors as an interesting case, which simply underlined the feelings I already had of freakishness,' said Anne, an AIS woman from Birmingham. Some seeking plastic surgery have been told 'wait until you get married'.

Helen discovered that she had AIS when she had not menstruated by the time she was 18. 'I was horrified. My doctor was very embarrassed and part of my dealing with it was coping with him. Optimistic but dismissive is the way I would sum up general attitudes to AIS. At times you ask yourself: Am I gay? Am I heterosexual?

'One of my reactions was a phase of promiscuity. I had to be more attractive than other women, I overexerted my feminineness. I am also quite bitter. I am genetically male, but I don't have the freedom to walk safely alone at night or go into a bar like they do. I'd like to get married, too, to be a member of a family unit. It would be nice, although I accept I cannot have children.'

Richard Lilford, professor of obstetrics and gynaecology at Leeds University and one of Britain's leading experts on AIS, said: 'We believe AIS affects around one in 50,000 births. The women are chromosomally male, but their tissue is not sensitive to male hormones.

'It has created ethical problems as to what and how much information to give to parents and patients. Obviously, it is very traumatic for a woman to be told she is genetically male. In some cases women have simply been told they cannot have children. But some clinicians believe that parents and the women themselves can cope better with the whole truth rather than half truths,' Professor Lilford said.

'Up to now I have tended not to tell them they have male chromosomes because that is very difficult information to assimilate. Once you have told them you cannot untell them.'

Mrs Burrows said: 'I want to make people aware of this condition. There has been so much secrecy that someone has to make a stand, someone has to come out and be identified.'

AIS Support Group: Jackie Burrows, 0623 661749.

Vaginoplasty Support Network North: Sheila Naish, Royd Well Counselling, 35 Royd Terrace, Hebden Bridge, West Yorkshire, HX7 7BT: 0422 845304.

Vaginoplasty Support Newtwork South: Hilary Everett, Social Services Department, St Bartholomew's Hospital, London, EC1A 7BE: 071- 601 8718.

(Photograph omitted)