The massive efforts to systematically find and catalog single nucleotide polymorphisms (SNPs) bear witness to the conviction that small genomic changes may provide clues to the origins of such things as heart problems, obesity, and pharmacologic responses.
But another type of variation, largely overlooked by the genetics community, might ultimately make equally important contributions to health. Large, submicroscopic rearrangements comprise about 5%-10% of the human genome. Many of these contain duplications that vary in the number of times and ways they are repeated: tandemly, at distal parts of the same chromosome, or even on other chromosomes.
At least three papers last summer dealt with the advantage of new technologies used to discover the extent to which these polymorphic rearrangements are duplications of genes found elsewhere in the genome. And research published in January documented the first instance of the resulting gene-dosage effect on disease susceptibility: the effect of copy number ...
