Mosaicism linked to increased cancer risk

The role of chromosomal structural abnormalities in the development of cancer has been at the center of a chicken-or-the-egg controversy for some time. Cancer cells often contain structural abnormalities, but it has been unclear whether (and which) chromosomal defects come first or are part of the oncogenic process. Now, two groups of investigators, led by National Cancer Institute (NCI) and the University of Washington, have independently concluded that older people harboring mosaic cells are at higher risk for some malignancies, including several types of hematologic cancers such as leukemias and lymphomas. The studies, published together online in Nature Genetics on 6 May 2012, provide the first large, systematic examination of genetic mosaicism in healthy populations. The authors found mosaic abnormalities most frequently in people with solid tumors (0.97% vs. 0.74% in cancer-free individuals). They studied blood samples from 50,000 participants per study, including more than 30,000 cancer patients in the NCI study. The number of people identified with genetic mosaicism was small (404 of the participants), and most of them were more than 50 years old. These individuals faced a 10 times greater risk of developing a blood cancer than those without genetic mosaicism, according to the retrospective analysis.

Don’t like meat? It might be genetic

People who say that pork tastes bad may be more sensitive to androstenone, a hormone produced by boars that is present in some meat. A recent study, conducted in Norway and published in the May issue of PLoS ONE, reported that people who have two copies of the human odor receptor gene OR7D4 said that pork with more androstenone tasted pungent or “urine-like” as compared with heterozygous participants carrying a single-nucleotide polymorphism variant conferring two amino acid substitutions. Although the sample size was small, with 23 participants, the findings have immediate implications because Norway is considering a ban on castrating boars, which would increase the amount of androstenone in meat. More broadly, research on the role of genes in taste is particularly interesting in light of the potential impact on nutrition and human health. A larger study comparing African populations recently showed that the gene responsible for conferring a bitter taste to broccoli and other cruciferous vegetables is uniform across Africa and is millions of years old, predating modern humans. That study, published 29 November 2011 in Molecular Biology and Evolution, also revealed that differences in local diets across the continent did not seem to have an effect on evolution of the gene, suggesting its importance in other aspects of human health.

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