Vietnam records rare identical twin pregnancy with different genotypes

Doctor Nguyen Thi Sim of the Hanoi Obstetrics and Gynecology Hospital on Wednesday said a 23-year-old woman was admitted 18-week pregnant. Tests and ultrasound scans revealed a male and a female fetus, with the male fetus possessing the 46XY genotype and the female possessing the 45X genotype.

Such a case is exceedingly rare in the world, Sim said. It is also the first known case for Vietnam, she added.

More tests have been conducted to figure out the root cause of the case. Doctors found out that the male fetus also lacks a Y gene section, which would affect its reproductive capabilities in the future.

“Tests also showed that the chance of stillborn is very high, up to 50%,” Sim said.

The twin was conceived naturally by a pair of parents with normal genomes. A test revealed that mutations happened while the twins were a zygote. The parents have decided to terminate the pregnancy.

Tran Duc Phan, head of the Vietnam Medical Genetics Association, said the couple can still have a normal pregnancy in the future with healthy babies. The case is also a reminder that doctors should not perform tests on one fetus only while ignoring the others in the case of multiple pregnancies.