Above is a family tree of more than 100 current-day Icelandic asthma patients, going back eleven generations to their common ancestors born in the 17th century.
While the DNA sequence is the ultimate fine-scale physical map of the human genome, working out that sequence – as was the goal of the Human Genome Project – has hardly put an end to mapping studies. The sequence itself is still continuously being updated and annotated; the NIH's National Center for Biotechnology Information released Build 35.1 in November. Moreover, other types of maps that are no less important for the positional cloning and candidate mapping methods geneticists use to search for disease-causing genes are still being crafted.
Linkage maps, which describe the frequency with which genetic markers are coinherited, are one example, as are single-nucleotide polymorphism (SNP) maps, which locate variable genetic sequences on the physical map. Linkage-disequilibrium (LD) maps, showing how SNPs ...
