Combining two Meishan F2 crosses improves the detection of QTL on pig chromosomes 2, 4 and 6.
BACKGROUND
In pig, a number of experiments have been set up to identify QTL and a multitude of chromosomal regions harbouring genes influencing traits of interest have been identified. However, the mapping resolution remains limited in most cases and the detected QTL are rather inaccurately located. Mapping accuracy can be improved by increasing the number of phenotyped and genotyped individuals and/or the number of informative markers. An alternative approach to overcome the limited power of individual studies is to combine data from two or more independent designs.


METHODS
In the present study we report a combined analysis of two independent design (a French and a Dutch F2 experimental designs), with 2000 F2 individuals. The purpose was to further map QTL for growth and fatness on pig chromosomes 2, 4 and 6. Using QTL-map software, uni- and multiple-QTL detection analyses were applied separately on the two pedigrees and then on the combination of the two pedigrees.


RESULTS
Joint analyses of the combined pedigree provided (1) greater significance of shared QTL, (2) exclusion of false suggestive QTL and (3) greater mapping precision for shared QTL.


CONCLUSIONS
Combining two Meishan x European breeds F2 pedigrees improved the mapping of QTL compared to analysing pedigrees separately. Our work was facilitated by the access to raw phenotypic data and DNA of animals from both pedigrees and the combination of the two designs with the addition of new markers allowed us to fine map QTL without phenotyping additional animals.
INRA, UMR 0444 Génétique Cellulaire, F-31326 Castanet-Tolosan, France.
Flavie
F
Tortereau
Hélène
H
Gilbert
Henri C M
HC
Heuven
Jean-Pierre
JP
Bidanel
Martien A M
MA
Groenen
Juliette
J
Riquet
D000273:Adipose Tissue; D000818:Animals; D002874:Chromosome Mapping; D033481:Chromosomes, Mammalian / Q000235:genetics*; D003433:Crosses, Genetic; D005260:Female; D005819:Genetic Markers; D008297:Male; D008460:Meat; D010375:Pedigree; D040641:Quantitative Trait Loci / Q000235:genetics*; D019655:Quantitative Trait, Heritable; D034421:Sus scrofa / Q000235:genetics*; D015430:Weight Gain / Q000235:genetics
D005819:Genetic Markers