Ana Paula Martins has XX chromosomes in all cells in the body, but in the blood carries xy, with male characteristics
Ana Paula Martins, a 35 -year -old Brazilian, was diagnosed with a rare genetic condition. The doctors found that the woman carried her brother Gemini’s blood cells. An unprecedented case in medicine, in a condition identified in Brazil that can open the door to understanding human genetics.
The discovery was made in early 2022, after Ana Paula had suffered a miscarriage. During the medical investigation, her gynecologist asked the patient to perform a karyotype: a medical examination that detects genetic changes.
Ana Paula, who works in the health area, told the exam results caused a “mega impact”, as they had the presence of XY chromosomes in the blood.
According to the gynecologist and professor at the Faculty of Medicine of the University of São Paulo Gustavo Maciel, the patient had all the female characteristics, such as the uterus and the normal and healthy ovaries, which aroused the interest of the medical community.
Ana Paula’s case came to the geneticist Caio Robledo, who explained to BBC Brazil that what caught her attention was that the patient had a normal sexual development, despite the genetic change.
“When we come across an XY karyotype in a woman, there are several rare diseases that can cause this situation. But almost all of them involve infertility and/or disability for the ovaries to function, both in the production of female hormones and in egg production and, consequently, in the possibility of a pregnancy. This scenario would be incompatible with pregnancy,” explains the geneticist.
Caio Robledo, along with Gustavo Maciel and other professionals, began a medical investigation that became a study. This research was conducted in the Fleury Group, HNO Ospital Israelite Albert Einstein and at the Clinical Hospital of the University of São Paulo School of Medicine.
During the investigation, Ana Paula mentioned that she had a twin brother, a revelation that turned out to be fundamental to understanding the case. The doctors compared the DNA of the twins and found that Ana Paula’s blood cells were identical to her brother’s.
“She has a part of her brother circulating inside her,” says Robledo. The doctors identified the situation as a case of chimerism, a condition caused by the presence of cells of two or more zygotes in the same individual. In other words, it is as if there were two people within the same body.
Despite being a genetic condition, chimmerism is not hereditary. Some medical treatments can lead to the condition, but spontaneous chimmerism is extremely rare.
Investigators suspect that during the twin gestation, the placentas or umbilical cords of the fetuses came into contact, forming a connection between the blood vessels. This contact would have allowed the boy’s blood to circulate to the girl’s body, where Ana Paula’s brother’s blood cells recolone her bone marrow. As a result, blood began to produce cells with XY chromosomes, while the rest of the body kept the XX standard.
“On the skin, in the DNA of the mouth, in the DNA of the skin, she is a person. In her blood, in the white blood cells, she is the brother – exactly the same as her brother,” said Gustavo Maciel.
Such a case had never been documented in medicine, but it can help researchers understand better issues related to human immunity.
During the study, and although people with this condition present infertility problems, Ana Paula became pregnant and gave birth to a healthy child. After birth, doctors performed a genetic analysis to the child, who revealed an DNA in the expected: 50% of the father’s chromosomes and 50% of the mother. The geneticists did not find any traces of Ana Paula’s brother’s DNA on his son.
Gustavo Maciel explains that “this case shows us that there may be some situations where there is immune tolerance, which may open research perspectives to better understand the issue of transplants, for example.”
For Ana Paula, it was important to discover and understand the origin of her genetic change, especially to ensure that she did not interfere with her pregnancy. “It was a relief to find out that this was not mine, that it was not my body that was producing,” explained the patient, “it was not something that could interfere with my goal, which was to have my baby.”
