Transcription-coupled TA and GC strand asymmetries in the human genome

Abstract Analysis of the whole set of human genes reveals that
most of them present TA and GC skews, that these biases are
correlated to each other and are speci¢c to gene sequences,
exhibiting sharp transitions between transcribed and non-tran-
scribed regions. The GC asymmetries cannot be explained solely
by a model previously proposed for (G+T) skew based on tran-
sitions measured in a small set of human genes. We propose that
the GC skew results from additional transcription-coupled mu-
tation process that would include transversions. During evolu-
tion, both processes acting on a large majority of genes in germ-
line cells would have produced these transcription-coupled
strand asymmetries.