A combination comprising two or more polynucleotides that are
differentially expressed in fat animals compared to lean animals or two
or more proteins produced by the expression of such polynucleotides is
disclosed. The combination and probes based upon the combination are used
for formulating a prognosis that an animal is likely to become fat,
developing a diagnosis that an animal is fat, screening substances to
determine if they are useful for modulating the amount of adipose tissue
on an animal, and detecting the differential expression of one or more
genes differentially expressed in fat animals compared to lean animals in
a sample. Methods for using class predictor gene profiles to identify fat
and lean animals are also disclosed.