Mapping and analysis of quantitative trait loci in experimental populations

Abstract

Simple statistical methods for the study of quantitative trait loci (QTL), such as analysis of variance, have given way to methods that involve several markers and high-resolution genetic maps. As a result, the mapping community has been provided with statistical and computational tools that have much greater power than ever before for studying and locating multiple and interacting QTL. Apart from their immediate practical applications, the lessons learnt from this evolution of QTL methodology might also be generally relevant to other types of functional genomics approach that are aimed at the dissection of complex phenotypes, such as microarray assessment of gene expression.

Immunological needles in the gene therapy haystack: applying a genetic paradigm to gene therapy

“…In the long run, the search aims to identify either a nucleotide polymorphism within the coding region that determines protein function, or a polymorphism within the promoter regions that affect the level of gene expression. [13][14][15][16][17][18] The power of the studies published is also necessarily limited to the QTLs defined a priori. Alternative hypotheses could propose, for example, that IFN-g released by subtypes of immune cells directly in the liver contributes to clearing of adenovirus from the liver.…”

“…Once identified, the QTL is most likely a polymorphism affecting protein function or the levels of protein expression. [13][14][15] To determine these QTL, they utilized 20 strains of recombinant inbred mice [16][17][18] derived from a cross between C57BL/6J and DBA/2J; 19 each recombinant inbred strain contains chromosomal regions that are derived from either parent, and they are homozygous at each locus (see Figure 1 for a schematic view of the production of recombinant inbred strains).…”

QTL mapping for protein content in soybean cultivated in two tropical environments

“…Single marker mapping and multiple regression analysis are important tools for preliminary studies to detect candidate QTL (Doerge, 2002). With the availability of high definition genetic maps, specific genome regions can be delimited and markers can be tested in different genetic backgrounds, speeding up QTL detection.…”

Intergenomic consensus in multifactorial inheritance loci: the case of multiple sclerosis

“…Such analyses have proven successful to identify genes and pathways determining the pathogenesis. 1 The process of reducing a previously determined QTL is referred to as fine mapping. Unfortunately, classical approaches for fine-mapping are time and cost intensive and experimentally complex.…”

“…2 In order to save resources, other techniques are used to direct the analysis of larger QTLs, for example, global analysis of single-nucleotide polymorphisms (SNPs), 3 large scale sequencing and gene expression profiling. 1 The latter point to genes that are differentially expressed in diseased animals, thus setting preferences among candidate genes within a QTL. This has been performed recently 4 for the mouse experimental autoimmune encephalomyelitis (EAE).…”