To do so, we examined the absolute levels of transcription, histone acetylation and DNA methylation for all subjects combined (Fig. S3), and compared them to previously published relationships between levels of gene expression, DNA methylation, and histone acetylation across 5' regulatory regions, exons, and introns.
Several studies conducted in organisms as diverse as humans, Drosophila melanogaster and Caenorhabidtis elegans, have demonstrated that there is an inverse relation between levels of gene expression and a variety of sequence parameters such as the length of coding sequence, intron number and length [1] [3].
However, the interpretation of the relationship between levels of gene expression and sex bias is not straightforward.
We observed very strong correlations for all studied species between levels of gene content variation and levels of gene sequence variation.
Associations between levels of gene expression and continuous clinical variables (maternal and gestational age, duration of labour) were determined by measuring the probability of significance associated with the Pearson correlation coefficient (using the TDIST function in Excel).
In order to elucidate the possible contribution of the lipogenic enzymes for fatty acid composition in SAT and muscle, the relationship between levels of gene expression and the content on main fatty acids was determined (Table 3).
Carmel and Koonin (20) examined the relationship between levels of gene expression and gene compactness measures and concluded that this relationship is 'universally non-monotonic', where genes with intermediate expression levels tended to be the least compact in four distantly related species (human, Drosophila melanogaster, Arabidopsis thaliana and Caenorhabditis elegans).
