a method for quantitative measurement of gene expression through multiplex competitive reverse transcriptase polymerase chain reaction amplification has been established which comprises isolating cellular mrna of a target gene and a housekeeping gene which are then reverse transcribed and specifically amplified in the presence of competitive templates such that a ratio of target to housekeeping gene is obtained and used to assess the amount of gene expression . this method is useful for analysis of the small specimens available from human subjects and will allow improved understanding of mechanisms of disease .