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A human chimera is a human with a subset of cells with a distinct genotype than other cells, that is, having genetic chimerism.In contrast, an individual where each cell contains genetic material from a human and an animal is called a human–animal hybrid, while an organism that contains a mixture of human and non-human cells would be a human-animal chimera.
The parents of such twins, who are typically both of mixed race, have a combination of alleles for light and dark skin in their genome. Each sperm or egg cell possesses a random selection of genes from its mother or father. While not the most probable event, a sperm or egg may randomly acquire, for example, mostly alleles that confer light skin ...
From this knowledge, ES cell contributions to chimeras have been developed. ES cells can be used in combination with eight-cell-and two-cell-stage embryos to make chimeras and exclusively give rise to the embryo proper. Embryos that are to be used in chimeras can be further genetically altered to specifically contribute to only one part of chimera.
[5] Vanishing twin syndrome has been characterized as the loss of a twin before 12 weeks of gestation, or early during the first trimester where it is uncommon for twin pregnancy to have been identified. [6] According to Boklage, most twin pregnancies are ultimately born as singles, and vanished twins are a possible source of abnormal cells. [7]
The human twin birth rate in the United States rose 76% from 1980 through 2009, from 9.4 to 16.7 twin sets (18.8 to 33.3 twins) per 1,000 births. [5] The Yoruba people have the highest rate of twinning in the world, at 45–50 twin sets (90–100 twins) per 1,000 live births, [6] [7] [8] possibly because of high consumption of a specific type of yam containing a natural phytoestrogen which may ...
Image credits: anothermegan #3. Me and my twin are complete opposites. I have a pixie cut and she has long hair. I am a musician and she is a mathematician. I am gay and she is straight.
Twins are concordant when both have or both lack a given trait. [ 1 ] The ideal example of concordance is that of identical twins , because the genome is the same, an equivalence that helps in discovering causation via deconfounding , regarding genetic effects versus epigenetic and environmental effects ( nature versus nurture ).
The cause of the condition lies in conception or utero with the aggregation of two distinct zygotes or blastocysts (one of which expresses 46,XX and the other of which expresses 46,XY) into a single embryo, [4] which subsequently leads to the development of a single individual with two distinct cell lines, instead of a pair of fraternal twins.