We examined the imprinting status of the insulin-like growth factor II
gene (IGF2) in a series of 20 human breast disease samples to determi
ne if disrupted imprinting (as evidenced by biallelic expression), was
a demonstrable mechanism of altered gene expression. These samples in
cluded benign (n = 7) and malignant breast lesions (n = 13). Biallelic
expression of IGF2 was detectable in 67% of benign and 60% of maligna
nt informative breast lesions. Three informative reduction mastectomie
s displayed normal IGF2 imprinting. The presence of this alteration in
human breast tissue is a novel finding, and may contribute to tumorig
enesis, possibly by favouring an enhanced proliferative milieu, during
which additional mutations could occur.