Global gene expression profiles in skeletal muscle of monozygotic female twins discordant for hormone replacement therapy

Analysis of gene expression profiles in skeletal muscle tissue after long-term use of HRT. Networks of enriched processes in skeletal muscle responding to long-term use of estrogen-based HRT in comparison with women without any HRT in a genetically controlled setting were contructed. The association between the expression of specific biological processes and muscle composition or performance was tested. The hypothesis was that the differences in gene expression profiles reflect the known differences in muscle composition and performance. Total RNA obtained from muscle biopsies (vastus lateralis) from genetically identical female twin pairs (n=11 pairs) of which one sister is a user of postmenopausal, estrogen-based HRT (n=11), while the other is a never-user (n=11).