This is the first time a case of such a rare identical twin pregnancy has been discovered in Vietnam, and it marks the second case in the world.
Medical literature notes that identical twins occur when a fertilized egg divides into two embryos, developing into two separate individuals. This process begins in the very early stages when the embryo is merely a cluster of cells. Identical twins will be completely similar in appearance and gender.
However, the case just announced by Hanoi Obstetrics and Gynecology Hospital is a remarkably rare case worldwide.
This is an extremely rare case, first discovered by Hanoi Obstetrics and Gynecology Hospital. (Illustrative photo).
The pregnant woman, aged 23, is experiencing her first natural pregnancy. An ultrasound revealed a shared placenta and two amniotic sacs from the 8th week of pregnancy. The woman visited the Fetal Intervention Unit at Hanoi Obstetrics and Gynecology Hospital for a check-up at 16 weeks due to one twin showing signs of swelling.
After consultation, ultrasound, and amniocentesis, it was found that Twin A exhibited swelling, is female, and has Turner syndrome (45,X). Twin B appeared normal in terms of morphology and was identified as male with a male genotype (46,XY). Additional in-depth genetic tests were conducted, confirming that the two twins originated from a single egg but have different genetic makeups.
Dr. Nguyen Duy Anh, Director of Hanoi Obstetrics and Gynecology Hospital, stated that this is an extremely rare case, and it is the first time it has been identified by the hospital.
Dr. Nguyen Thi Sim, who directly conducted the tests that revealed the abnormal twin pregnancy, noted: “The findings from Hanoi Obstetrics and Gynecology Hospital show that some identical twins can have 100% differences in genetic and phenotypic traits. With comprehensive diagnostic capabilities and modern equipment, the hospital can conduct examinations, ultrasounds, and in-depth genetic tests that help identify many rare cases. This unique case has provided a completely new, broader perspective for the fields of Genetics and Obstetrics.”
It is known that this case underwent thorough consultation, with advanced genetic tests indicated right from the prenatal stage, resulting in abnormal findings. This case suggests that when abnormalities are present, genetic testing is necessary.
Dr. Nguyen Duy Anh emphasized that this case highlights the need for genetic testing when abnormalities are detected. “This discovery by the doctors at Hanoi Obstetrics and Gynecology Hospital shows that not all identical twins are genetically identical, and it is crucial not to overlook rare cases or genetic abnormalities,” Dr. Anh remarked.
Due to the genetic abnormalities of the fetus and the challenges in maintaining the pregnancy, the family opted to terminate the pregnancy. Notably, the male twin, due to genetic abnormalities, would not be able to reproduce if born and raised.
“Determining the causes of these abnormalities is very difficult. We can rule out pre-existing factors from the parents. These are cases of new mutations. This is a rare occurrence involving multiple genetic abnormalities,” stated Dr. Tran Duc Phan, President of the Vietnam Genetics Society.
