Quantitative Trait Locus Analysis Using J/qtl

Quantitative trait locus (QTL) analysis is a statistical method to link phenotypes with regions of the genome that affect the phenotypes in a mapping population. R/qtl is a powerful statistical program commonly used for analyzing rodent QTL crosses, but R/qtl is a command line program that can be difficult for novice users to run. J/qtl was developed as an R/qtl graphical user interface that enables even novice users to utilize R/qtl for QTL analyses. In this chapter, we describe the process for analyzing rodent cross data with J/qtl, including data formatting, data quality control, main scan QTL analysis, pair scan QTL analysis, and multiple regression modeling; this information should enable new users to identify QTL affecting phenotypes of interest within their rodent cross datasets.