Nested association mapping

Nested association mapping (NAM) is a technique designed by the labs of Edward Buckler, James Holland, and Michael McMullen for identifying and dissecting the genetic architecture of complex traits in corn (Zea mays).

NAM was created as a means of combining the advantages and eliminating the disadvantages of two traditional methods for identifying quantitative trait loci: linkage analysis and association mapping.

Association mapping, by contrast, takes advantage of historic recombination, and is performed by scanning a genome for SNPs in linkage disequilibrium with a trait of interest.

[3] This initial sequencing discovered 1.6 million variable regions in maize, which is now facilitating analysis of a wide range of traits.

[4] The first publication in which NAM was used to identify QTLs was authored by the Buckler lab on the genetic architecture of maize flowering time, and published in the summer of 2009.

These relatively small QTL effects, however, were also shown to sum for each family to equal large differences and changes in days to silking.

These observations led the authors to propose a model of "Common genes with uncommon variants"[4] to explain flowering time diversity in maize.

They tested their model by documenting an allelic series in the previously studied maize flowering time QTL Vgt1 (vegetation-to-transition1)[5] by controlling for genetic background and estimating the effects of vgt1 in each family.