March 21, 2004

Jane's unrelated sons. "Jane" is a human chimera; the product of two fertilised eggs whose DNA is mixed in the same body - and some of her children are descended from eggs containing one set of DNA, while others come from an entirely different strain. As this Nature article explains, the level of mixing can range form the trivial to the profound, and can result in non-hermaphroditic gender mixing in the same person, with an XY lung and an XX kidney.
posted by rodgerd 20 years ago
  • the remarkable leaps of science are starting to be very unsettling in what they reveal. perchance greek mythology was more based in fact than we care to believe. rodgerd, thank you for more wonderful information....very provocative.
  • I read about this a couple of months ago - its pretty amazing. I wonder how common it actually is.
  • Fascinating subject, rodgerd. The things we think we know often turn out to be not so...
  • All of us would be mosaics to some degree. The threshold at which one is called a mosaic is arbitrarily set.
  • Hm? But I thought mosiacs have parts of their bodies which are genetically different from the other parts. Would most humans not have genetically uniform bodies? I mean that if a hair sample, saliva sample and other...stuff... from one person were given DNA tests, a mosaic may have different results for the different samples, but a 'normal' (for want of a better word - which I'm too lazy to look for right now) person would have the same results throughout?
  • Very interesting. Thanks, rodgerd.
  • All of us would be mosaics to some degree. Sooooo, Gyan if a monkey were to serve on a jury where DNA was part of the evidence, what conclusions should we bear in mind relative to this?
  • This is incredible. My mind is buzzing with the possibilities this presents. Fantastic post, rodgerd.
  • It deserves to be said that having a non-uniform bodily phenotype (mosaicism) is fairly common. The sex with two identical sex chromosomes (females in mammals, males in birds and some insects) are capable of having a mosaic phenotype, due to the fact that one of the doubled sex chromosomes (the X chromosome in mammals) is silenced for the sake of controlled gene dosage (in a form called a Barr body). If one of the X chromosomes contains a mutation that carries a noticable phenotype, this will cause mosaicism where patches of the body have the same phenotype, with two types of patches (see 14. mosaicism here). The actual chromosome that becomes a Barr body appears to be randomly determined, but it is decided at a certain point during development so that the developed organism has a patchiness. This is capable of occurring in male mammals with Klinefelter syndome (one possibly NSFW clinical photo)(each cell containing two or more X chromosomes and a Y chromosome), with a famous and very visual example being tortoiseshell tomcats (female calicos (forgive the inane captions) also have a mosaic phenotype). That said, in the context of experiments chimaeras have been used for years, even to the extent of having cells from multiple species: chimera (chimaera): An organism which contains cells or tissues with a different genotype. This can result from mutated cells within the developing embryo of a single organism. It can also result from mixing cells from different individuals of the same species, or of individuals from different species. Fusion of embryos or insertion of cells from one embryo or from stem cells into another organism can be used to create chimeras. For example, laboratory mice have been created with human immune systems for the purpose of understanding various aspects of immune response. Chimeras can also result from grafting of tissue from one plant type onto another such as is done in agriculture (graft hybrid). Chimeras are also said to represent "genetic mosaics". Organisms which express both male and female characteristics by virtue of being a mosaic of male and female cells are referred to as "gyandromorphs'. The mythological chimera had the head of a lion, the body of a goat, and the tail of a serpent.
  • Like Darshon, my mind is buzzing. Thanks, jray, for the links.
  • La femme est la chim
  • Gyandromorphs?
  • Oh god that's beautiful, Wolof -- thanks!
  • Bees, the other Chim
  • jjray - thanks. had i been here earlier i would have used the same example (barr bodies) but you beat me to the punch...
  • Wolof -- thank you very much for that link.
  • I was talking about this with my wife and realised how fortunate "Anne" is in one sense; as a woman, the genetic difference in her children cause people to look for a (fairly exotic) answer; if the same thing happened with a man producing different genetic profiles, I imagine they would have assumed unfaithfulness in the childrens' other parent.
  • That's a scary thought. I recall reading once that as much as 30% of children born in the US had blood types that were incompatible with their mothers' husbands (that is, their legal father could not have been their biological father). I'd imagine a certain percentage of those children were actually conceived by their legal parents.
  • Monkeyfilter: "My wink-wink calls me his Patchwork Princess and that makes me sooooo happy!" Fascinating links, by the way.
  • do you think jerry springer and phil donahue should be alerted to these possibilities? i suppose not, it wouldn't help their ratings at all.
  • Wolof I was wondering what you were getting at, with Gyandromorphs. Then I realized that you're pronouncing my name wrong. It's monosyllabic. Gyaa - n.
  • Great links, jjray! Thanks!
  • I pronounce not. I spell. All day spelling, never pronouncing. Never make link between exact same spelling because pronounce different. Never make pun, especially visual. Never play. Worse off all is interlingual bun. Dull boy.
  • Wolof, I think you're on the wrong thread? Shouldn't you be over here instead? Would you like me to email you some buns?
  • Holy crap. This is amazing. Thanks for the link!
  • Semi-identical twins discovered These twins, who were conceived normally, only came to the attention of scientists because one was born with sexually ambiguous genitalia. The child was discovered to be a hermaphrodite, and has both ovarian and testicular tissue, while the other child is anatomically male. But genetic tests show both are "chimeras"