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Two imprinted genes identified using DNA microarrays
Edward R. Winstead

Scientists have used DNA microarrays to identify two mouse genes that appear to be imprinted. Unlike most genes, imprinted genes are expressed differently depending on which parent they came from. Defects in imprinted genes can cause mental retardation and developmental disorders in humans, including such rare but medically important disorders as Angelman syndrome, Prader-Willi syndrome, and Beckwith-Wiedemann syndrome.

Rebecca J. Oakey, of University of Pennsylvania School of Medicine in Philadelphia, and colleagues were trying to see whether they could use microarrays to detect the altered expression of five imprinted genes in mice when they discovered the two other imprinted genes. The strategy they were testing seemed to work: The study correctly identified four out of five imprinted genes represented on a microarray based on gene expression.

Microarrays are sensitive enough to detect differences in gene expression associated with imprinting, the researchers conclude. They add, however, that to interpret expression data accurately, one needs to know the genetic background of the mice, which tissues were profiled, and the developmental stage in which the profiling was performed.

"These results show proof of the concept that by using genetic tools of a defined phenotype, imprinted genes can be identified in a systematic and tissue-specific way," the researchers write in Mammalian Genome. One of the two imprinted genes identified in this study had not been previously reported in the literature.

The mouse microarray in the study contained DNA from five imprinted genes on chromosomes 7 and 11. These chromosomes contain at least 30 imprinted mouse genes. The number of known human imprinted genes is approaching 50.

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Choi, J.D. et al. Microarray expression profiling of tissues from mice with uniparental duplications of chromosomes 7 and 11 to identify imprinted genes. Mamm Genome 12, 758-764 (October 2001).

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