# How to compare two series of gene expression levels?

I have a data set with gene expression levels measured for three different treatments, and for each treatment we have three biological replicates. Treatments are: Control, 24h at $4$°C, and 24h at $-3$°C. This analysis was carried out on two genotypes.

                       CTRL1 CTRL2 CTRL3 4°C_1 4°C_2 4°C_3 -3°C_1 -3°C_2 -3°C_3
Gene1  Genotype 1       20    22    25     85    92    120   450    380    372
Genotype 2       50    72    78     130   122   184   250    490    700


I'd like to know how to compare gene1 expression level in genotype1 vs. genotype2. The aim is to find a similarity between expression trend in genotype1 and genotype2.