'Semi-mono twin birth' which is impossible usually is reported during pregnancy for the first time in the world
The identical twins sharing DNA have the same sex, and the state "boys and girls of identical twins" is usually impossible. However, researchers from Brisbane, Australia reported this very rare case.
Molecular Support for Heterogonesis Resulting in Sesquizygotic Twinning | NEJM
First semi-identical twins identified in pregnancy - ScienceDaily
Scientists stunned by discovery of 'semi-identical' twins | Science | The Guardian
In identical twins, DNA is shared with the same gender, usually because one sperm and egg are fertilized and the fertilized egg is divided into twins. On the other hand, gymnosyndrops are born of separate eggs fertilized with sperm, so there are cases where gender is different.
However, according to the report by Dr. Ikel Gabet of the Queensland Institute of Technology, it is confirmed that a semi-identical twin that extremely rare "two sperm simultaneously fertilized in one egg" was confirmed .
According to researchers, semi-mono twin children are 4 years old as of February 2019. Twin mothers living in Brisbane, Australia received an ultrasonic examination at the sixth week of pregnancy and said that they were judged as "twins are identical twins" because they had one placenta and amniotic cavity. However, at the 14th week of pregnancy it turned out that the twins are girls and boys. This is unlikely to be an identical twin.
When one ovum is fertilized with two spermatozoa, the number of chromosomes is one set from mother and two sets from father, totaling three sets. Fertilized eggs with three sets of chromosomes usually can not survive. However, the twins reported by Dr. Gabbet et al. Seem to have divided the three sets of chromosomes equally to make a cluster of cells, then divide into two and become twins. Some of the cells have the first sperm chromosome and the other cells have the second sperm chromosome so that they do not share the DNA completely, but rather share the twins in a partially shared form It is said that it was created.
Semi-monozygotic twins were reported in the United States in 2007 as well. The twins, in 1 person childhood intersex thing and drew the doctor's attention to the opportunity that it has been determined that it is. When the chromosome was examined, the chromosome of boys and girls was consistent with that of mother's side, but said that father's DNA was shared only by half.
In the case of Brisbane there was no report of intersex and children born by caesarean section looked healthy for both males and females. However, shortly after birth, a thrombus was found in the girl and forced cutting of the arm in four weeks after birth. In addition, it turned out that the ovaries of girls were not completely formed at the age of 3, and the ovaries were excised as it was considered to increase the risk of cancer.
During pregnancy, semi-identical twins were discovered in the case of Brisbane. The researchers thought that "There are few cases of semi-mono twins, probably because doctors misdiagnosed or not reported," probably because there are cases, genetic data of twin egg twins and their parents 968 It is said that they analyzed minutes. However, there was no data showing semi-monozygotic twins, and no reports were found in worldwide research.
in Science, Posted by darkhorse_log