FOUR out of ten women who conceive non-identical twins lose one of them early
in pregnancy. Now this mystery of the vanishing twin has been pinned to a single
gene.
Andreas Busjahn and his colleagues at Infogen and the Max Delbr眉ck
Centre for Molecular Medicine in Berlin studied non-identical twins to see which
versions of a gene called PPAR&ggr; they had inherited. They found the same
version of the gene in far more pairs of non-identical twins than expected (
Nature Genetics, vol 26, p 398).
This suggests that sharing the same gene variant gives non-identical twins a
big advantage in the womb, says Busjahn. PPAR&ggr; influences growth and
weight gain during development, so twins who carry the same gene variant may
develop at the same pace, with neither outcompeting the other.
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