Scan of human genome reveals no new Loci under ancient balancing selection.

There has been much speculation as to what role balancing selection has played in evolution. In an attempt to identify regions, such as HLA, at which polymorphism has been maintained in the human population for millions of years, we scanned the human genome for regions of high SNP density. We found 16 regions that, outside of HLA and ABO, are the most highly polymorphic regions yet described; however, evidence for balancing selection at these sites is notably lacking--indeed, whole-genome simulations indicate that our findings are expected under neutrality. We propose that (i) because it is rarely stable, long-term balancing selection is an evolutionary oddity, and (ii) when a balanced polymorphism is ancient in origin, the requirements for detection by means of SNP data alone will rarely be met.

Hypervariability, suppressed recombination and the genetics of individuality.

We define 'genetic individuality' as intraspecies variation that has substantial heritability and involves traits that are sufficiently common that they can be observed in any modest-sized sampling of individuals. We propose that genetic individuality is largely shaped by the combinatory shuffling of a modest number of genes, each of which exists as a family of functionally and structurally diverged alleles. Unequivocal examples of such allele families are found at the O-antigen-biosynthetic locus in Pseudomonas aeruginosa and the human leucocyte antigen locus in humans. We examine characteristic features of these allele families and explore the possibility that genetic loci with similar characteristics can be recognized in a whole-genome scan of human genetic variation.

Patient education and multiphasic screening: it can change behavior.

Two hundred ninety-two residents of Sonoma County, California, underwent multiphasic screeening and two sessions of group patient education aimed at reducing risk factors for cardiovascular disease, cancer, and automobile accidents. Approximately one year later all the participants were retested. A significant reduction was noted in systolic blood pressure in men and women, ages 50 to 70, cholesterol in men over age 40, and reported alcohol consumption in men. A significant increase was noted in the reported frequency of monthly breast self-examination in women, and in the amount of exercise and percentage of time seat belts were used in both sexes. No change was noted in reported amount of cigarette smoking, weight, fasting blood glucose, and triglycerides. The combined use of health hazard appraisal, multiphasic screening, and patient education can lead to a reduction in cardiac and other risk factors in well-motivated groups.