A brother and sister born in Australia in 2014 joined an exclusive club of brothers and sisters who share an extremely rare relationship – they are the second pair of "semi-identical" twins that have ever been discovered.
Each twin has received a DNA mess from a father, but the genes inherited from mom are 100% identical. Not only is one such case known, but this pair was the first one to have been discovered before it was born.
"The mother's ultrasound at six weeks showed a single placenta and positioning of amniotic bags, indicating that it expects identical Gemini," said Nicholas Fisk, a fetal care specialist, who cares for the young family before being based in Royal Brisbane and Women's Hospital four years ago.
It's possible for twins.
Usually twins are only two varieties. There is an unidentified "dissect" species, which is the result of two oocytes fertilized by separate semen.
Then there are ones that are identical, or "monozygotic," where a single fertilized egg divides entirely into individual individuals. before establishing itself in its expected growth and development program
Before 2007, the very idea of a third "semi-subsygro" category was more theoretical than the established fact. Then came an accidental discovery of twins born in the United States who turned out to be genetic chimeras. Both babies have a combination of cells, some with two X chromosomes and others with Y chromosome. If one of the babies is not born in an intersex, we may not be wiser than their genetic secret. Similarly, while none of the Australian twins physiologically are not present as an intersex, both have an assortment of cells that carry either XX or XY chromosomal pairs.
The study of cells taken from their respective amniotic fluid bags also showed that while the maternal DNA of each is 1
There is another option, preferred by the specialists researching the latest. "Probably the mother's egg was fertilized with two of the father's sperm before she was separated," Fisk says.
Like this friend who marks together at first date, an additional salesman Avoidance of genes should lead to a catastrophe for any romance, which means that such a new fertilized embryo would not normally be expected to do so. In the case of [Australian] sequoiatic twins, the fertilized egg seems to have divided three groups of chromosomes into groups of cells, which then divide into two, creating the twins, "says clinical geneticist Michael Gaby of the University of Technology Queensland, Australia
With so few examples that it is difficult to understand, it is difficult to know for sure which explanations are more accurate, or that each set of twins develops in a slightly different way. how many twins are considered non-identical, actually share the same DNA selection of their mother.
Investigating global databases of twins suggests that if there are others, they are still extremely rare examples. He first asked if there were other cases that were wrongly classified or not reported, so genetic data from 968 double twins and their parents were investigated, FISK said. in these data, nor the case of semi-identical twins in large global twin studies. "
Such a rarity excludes any case of routine genetic screening for twin chimerism at least for the time being
Progress in Genetic Screening and Expansion of Medical Data Databases could lead to the discovery of more semi-identical twins in the future and probably will help us better understand the fertilization process
Meanwhile these twin kits can legitimately
This study is published in The New England Journal of Medicine