1. Physiol Genomics. 2005 Mar 21;21(1):112-6. Epub 2005 Jan 4.
Complete and overlapping congenics proving the existence of a quantitative trait
locus for blood pressure on Dahl rat chromosome 17.
Grondin M(1), Eliopoulos V, Lambert R, Deng Y, Ariyarajah A, Moujahidine M, Dutil
J, Charron S, Deng AY.
Author information:
(1)Research Centre, Centre Hospitalier de l'Universite de Montréal (CHUM),
Montréal, Québec, Canada.
Linkage studies suggested that a quantitative trait locus (QTL) for blood
pressure (BP) was present in a region on chromosome 17 (Chr 17) of Dahl
salt-sensitive (DSS) rats. A subsequent congenic strain targeting this QTL,
however, could not confirm it. These conflicting results called into question the
validity of localization of a QTL by linkage followed by the use of a congenic
strain made with an incomplete chromosome coverage. To resolve this issue, we
constructed five new congenic strains, designated C17S.L1 to C17S.L5, that
completely spanned the +/-2 LOD confidence interval supposedly containing the
QTL. Each congenic strain was made by replacing a segment of the DSS rat by that
of the normotensive Lewis (LEW) rat. The only section to be LL homozygous is the
region on Chr 17 specified in a congenic strain, as evidenced by a total genome
scan. The results showed that BPs of C17S.L1 and C17S.L2 were lower (P < 0.04)
than that of DSS rats. In contrast, BPs of C17S.L3, C17S.L4, and C17S.L5 were not
different (P > 0.6) from that of DSS rats. Consequently, a BP QTL must be located
in an interval of approximately 15 cM shared between C17S.L1 and C17S.L2 and
unique to them both, as opposed to C17S.L3, C17S.L4, and C17S.L5. The present
study illustrates the importance of thorough chromosome coverage, the necessity
for a genome-wide screening, and the use of "negative" controls in physically
mapping a QTL by congenic strains.
PMID: 15632271 [PubMed - indexed for MEDLINE]
PUBMED: 15632271
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