Why there is 2 copy numbers for same patients for the same gene?

Question

[mms140130]

I have the CNV downloaded from TCGA2STAT in R, for BRCA patients. The data looks as follows:

gene    TCGA-3C-AAAU    TCGA-3C-AAAU
A1BG    0.1302  0.0064
A2M     0.2586  0.0033
A2MP1   0.2586  0.0033
NAT1    0.2662  0.0034

The same patient has 2 different CNV values for the same gene, why?

Answer 1

[Emily]

Probably because they have two copies of every gene (unless they're male, then they have two copies of most genes and one copy each of X and Y chromosome genes).