Health Tech

What Is The Secret Of Finding Male XY Chromosomes In A Woman’s Body

Every second cell in Ana Paula Martins’ body has X-X chromosomes, which are associated with the sexual characteristics of women. But her blood cells have XY chromosomes, which are normally found in men.

Doctors believe that this is a unique case, which has been reported for the first time. They speculate that her blood cells may have come from her twin brother while in the womb. This was first known when Ana Paula had a miscarriage in 2022. During the examination, a gynecologist asked for a karyotype test.

In this test, the chromosomes of a person’s cells are examined. Usually this test is done through a blood sample. “The lab contacted me and told me I had to get tested again,” Ana Paula says. The test results showed XY chromosomes in her blood cells, which surprised both her and the doctors. Gustavo Maciel is a gynecologist at Brazilian healthcare organization Fleuri Medicina a Saud and a professor at the University of São Paulo’s School of Medicine.

“I examined the patient and saw that all her physical characteristics were exactly like a normal woman,” he says. “She had a uterus and ovaries. The ovaries were functioning normally,” he says. Ana Paula was referred to Dr. Caio Quiño, a geneticist at the Albert Einstein Israelite Hospital in São Paulo, who began a medical examination with Professor Maciel and other specialists.

‘She has a bit of her brother’

During the research, Ana Paula revealed that she had a twin brother, and this fact proved to be crucial in understanding the case initially. Comparison of their DNA showed that only Ana Paula’s blood cells were exactly like her twin brother’s. They had the same special genetic markers.

“The DNA in her mouth and skin was the same. That was her identity, but in her blood… she was carrying her brother’s identity,” explains Professor Maciel. Ana Paula’s case is called a chimera, when a person has two types of DNA in their body.

Certain treatments can cause chimerism – such as a bone marrow transplant. For example, when donor cells are given to leukemia (blood cancer) patients, they repopulate their bone marrow.’ But naturally occurring chimeras are ‘extremely rare’, explains Prof Maciel.

While reporting the discovery in Scientific Research Publications, the researchers found a few cases of twin pregnancies in other mammals where blood was exchanged between the fetuses of different sexes.

The researchers think that Ana Paula’s placenta and her brother’s placenta somehow connected while she was in the womb, creating a connection between blood vessels that allowed the boy’s blood to flow to the girl.

According to Professor Maciel, “There was a transfusion process that we call fetal-fetal transfusion. At some point, the veins and arteries of both got connected in the umbilical cord. The brother gave all his blood substance to the sister.”

“The most surprising thing is that this substance remained inside her throughout her life,” he says.

It is believed that the blood cells of the brother made their way to Ana Paula’s bone marrow, and then she started producing blood that had XY chromosomes. While the rest of the body remained XX chromosomes. So it can be said that a little bit of the brother is still flowing inside her.

Rare but successful pregnancy

Scientists believe that this unusual case can open new directions for research on the immune system and human reproduction. Ana Paula’s body tolerated her brother’s cells without attacking them. “Her case gives us a new perspective on organ transplantation,” says Professor Maciel. “This could provide an opportunity for research to better understand complex problems like this.”

There have been reports of women having XY chromosomes in some rare cases, but usually this causes fertility problems. This did not happen with Ana Paula. She became pregnant and gave birth to a healthy son. Genetic tests clearly showed that the baby’s DNA was completely normal. Half from the mother and half from the father. There was no trace of Ana’s maternal uncle, Ana’s brother.

Professor Maciel explains, “Ana Paula’s egg contained her own genetic material. Her brother’s cells in her body did not interfere with the pregnancy.” It was important for Ana Paula to find the cause of this genetic change and more importantly, to ensure that it did not affect her pregnancy. In her words, “This was not an obstacle to my goal. My goal was to become a mother.”

What is the difference between XY and XX chromosomes?

XY chromosomes are sex-determining chromosomes found in humans and many other organisms. Normally women have XX chromosomes and men have XY chromosomes. There are a total of 46 chromosomes (23 pairs) in the human body, of which 22 pairs are normal i.e. autosomes and the 23rd pair is sex chromosomes. This pair determines the sex of a person. In normal circumstances, XY combination means male and XX means female.

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