MA plots of MMU16 trisomic and disomic microarray probes support the gene dosage effect hypothesis.

M is the average log2 fold change in intensity of fluorescence in the trisomic compared to the disomic (as a control). A is the average log2 intensity of fluorescence for both genotypes. The majority of expressed probes to genes located in the trisomic region had an M value of ∼0.58 =  fold change ∼1.5 (marked by a black dashed line), compared to the majority of disomic probes which have an M value of 0 =  fold change 1. The red dashed line is the line of loess fit to the M values.