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Aberrant meiotic recombination can result in disease-causing chromosome microdeletions or microduplications. A new study of several disease-associated recombination hot spots in male germ cells shows that some genomic rearrangements, particularly microduplications, are significantly underdiagnosed.
Breast tumors with deficiency in DNA double-strand break repair might be expected to show aneuploidy. A new study shows that microdeletions in PTEN, resulting in complete loss of PTEN protein, are signature lesions in these cancers, particularly those arising in BRCA1-mutation carriers.