Teen almost lost ovaries at birth over gender mix-up

Twins in the uterus sometimes shared some blood. In the girl's case her brother's blood became "engrafted". Photo / Thinkstock

A healthy young woman of 19 had a narrow escape from losing her ovaries at birth because of confusion over her sex, according to a report on her in today's New Zealand Medical Journal.

Though she had the external organs of a female, doctors at Starship children's hospital in Auckland were convinced, based on tests, that she was genetically male, without testicles.

She is a twin. During pregnancy, nasal abnormalities were detected in her and some amniotic fluid was removed from around both fetuses. This showed both had the male Y chromosome, a finding confirmed in the girl by blood tests at birth.

"Ultrasound scans demonstrated the presence of a uterus and fallopian tubes, but gonads [ovaries or testicles] were not visible," the journal article says.

She was diagnosed with "XY gonadal dysgenesis", which is having the male chromosome, but only "streak gonads" - fibrous tissue - instead of proper ovaries or testicles, which are at risk of developing cancer years later.

"I recommended a surgical exploration and the removal of that tissue," Starship paediatrician Professor Paul Hofman, who cared for the girl and is an author of the journal article, told the Herald.

"Thankfully her mother had the sense to ignore what I said."

The parents declined the "gonadectomy" operation and asked for no further follow-up until it was time for treatment to induce puberty, needed because of the supposed absence of gonads.

At 9 the girl was brought back to hospital after her breasts started developing. A gonad-related tumour producing oestrogen was suspected but tests ruled this out and natural puberty was confirmed.

An MRI scan identified normal female genital organs, including, unexpectedly, ovaries. Other tests confirmed she still had the male chromosome in her blood.

"She is a chimera, where you are made up of two separate individuals," Professor Hofman explained.

Twins in the uterus sometimes shared some blood. In the girl's case her brother's blood became "engrafted".

"The blood, which had some stem cells in it, which makes all the blood components, got into her bone marrow and, if you like, took over from her own bone marrow.

"Her bone marrow became [the same as] her brother's, just like a bone marrow transplant in an older person with leukaemia, their blood will be very different from the rest of their tissue."

Babies whose sex-chromosome in their blood was the opposite of their physical make-up had been rarely reported but it was probably more common than thought.