Part 3.Many investigators would like to
discover the set of downstream targets of a gene of interest.
In a genetic and
functional sense, that question can only be addressed effectively if there
is genetic variation in the particular gene.We know that Fos is an important transcription factor,
but unless it is polymorphic between C57BL/6J and DBA/2J, then it cannot
generate a genetic variance signal with which we can work. We can still
study covariance of Fos and hundreds of other transcripts (an interesting
exercise), but there are no genetic causes-and-effects.