Frequent loss of imprinting of PEG1/MEST in invasive breast cancer

The human PEG1 gene is a newly identified imprinted gene on 7q32, Genetic a berrations of this chromosomal region are often detected in invasive breast carcinomas. In this study, we show monoallelic PEG1 expression in normal b reast tissue, indicating the presence of a functional imprint, and more imp ortantly, we demonstrate loss of imprinting (LOI) in all of seven informati ve invasive breast carcinomas. In contrast to this, in one case of atypical ductal hyperplasia (ADH) found in residual breast, imprinting was maintain ed, This raises the possibility that aberrant imprinting of PEG1 may be inv olved in the progression from hyperplasia to invasive breast cancer.