Nature genetics
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PALB2 interacts with BRCA2, and biallelic mutations in PALB2 (also known as FANCN), similar to biallelic BRCA2 mutations, cause Fanconi anemia. We identified monoallelic truncating PALB2 mutations in 10/923 individuals with familial breast cancer compared with 0/1,084 controls (P = 0.0004) and show that such mutations confer a 2.3-fold higher risk of breast cancer (95% confidence interval (c.i.) = 1.4-3.9, P = 0.0025). The results show that PALB2 is a breast cancer susceptibility gene and further demonstrate the close relationship of the Fanconi anemia-DNA repair pathway and breast cancer predisposition.
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Mammalian telomeres have epigenetic marks of constitutive heterochromatin. Here, we study the impact of telomere length on the maintenance of heterochromatin domains at telomeres. Telomerase-deficient Terc(-/-) mice with short telomeres show decreased trimethylation of histone 3 at Lys9 (H3K9) and histone 4 at Lys20 (H4K20) in telomeric and subtelomeric chromatin as well as decreased CBX3 binding accompanied by increased H3 and H4 acetylation at these regions. ⋯ In contrast, telomere repeat factors 1 and 2 show normal binding to telomeres independent of telomere length. These results indicate that loss of telomeric repeats leads to a change in the architecture of telomeric and subtelomeric chromatin consisting of loss of heterochromatic features leading to a more 'open' chromatin state. These observations highlight the importance of telomere repeats in the establishment of constitutive heterochromatin at mammalian telomeres and subtelomeres and point to histone modifications as important in counting telomere repeats.