Study of gene expression of peripheral blood T lymphocytes from age-series of monozygotic twin couples

In this study we analyse a gene expression dataset, obtained by microarray hybridization, consisting of T lymphocytes from 27 healthy monozygotic twin couples with ages ranging over whole adult lifespan (22 to 98 years). This peculiar experimental design, combined with a ridge regression approach, allowed us to define an optimal low-dimensional gene expression signature from which chronological age can be estimated. Our work identified for the first time a group of 125 genes whose expression can be considered a signature of physiologic T cell aging. This signature has been further validated in another dataset of samples of the same cell type, but hybridized over a different platform, showing a significantly good performance that confirmed the power of the chosen analysis design. Moreover, the same signature was applied on a publicly available dataset with an analogous time series design, but hybridized on a different platform and consisting of a different cell type (human muscle cells). The lower regression performance obtained in this case indicates that the signature is cell-type specific. 27 couples of monozygotic twins (54 subjects in total, homogeneously distributed in an age span from 22 to 98 years) were analysed.