The First Genome-Wide Human Genetic Map Was Created by Taking

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The Answer is In model organisms, genetic mapping relied on phenotypes. That is the genetic maps were obtained by mapping gene mutations that cause readily identifiable phenotypes. In Drosophila, for example, crosses can easily be set up to breed mutant white-eyed flies with flies that have abnormal curly wings; the progeny are then examined to see if the two mutant phenotypes segregate together or not. In humans, however, that kind of approach could never be applied-a different strategy was needed.
Instead of having a genetic map based on gene mutations, the solution to making a human genetic map was to identify general DNA variants (that mostly do not map within coding sequences, and usually have no known effects on the phenotype). Different types of variants were identified and mapped to specific locations in our genome, beginning with restriction fragment length polymorphisms (RFLPs) that created or destroyed a restriction site followed by microsatellite polymorphisms that varied in the copy number of short tandem repeats. These provided anonymous genetic markers for each chromosome and the segregation of alleles at these marker loci were then followed through multigeneration families to identify neighboring markers (because their alleles would tend to segregate together).

The First Genome-Wide Human Genetic Map Was Created by Taking

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