Gene set enrichment analysis — A limitation of GO analysis is that the predetermined categories may not match the ones of functional
interest in a particular tissue.
Degenerative aging is a consequence of the progressive accumulation of damage to tissue cellular and molecular structures over time; specific diseases of aging emerge when the cumulative burden of such
damage in a particular tissue exceeds the minimum required to sustain its core biological functions.
To investigate this question, Fallin and her colleagues started by surveying four different tissue types — blood and cord blood from their own collections, as well as lung and fetal brain tissue from public collections — to find small variations in the genetic code of each sample that appear to be responsible for DNA methylation state, a type of epigenetic modification,
in that particular tissue.