Dunn, Ian Chisholm. (2019). An eQTL in the cystathionine beta synthase gene is linked to osteoporosis in laying hens, [dataset]. University of Edinburgh. The Roslin Institute. https://doi.org/10.7488/ds/2619.
"An eQTL in the cystathionine beta synthase gene is linked to osteoporosis in laying hens"
Dirk-Jan De Koning, Nazaret Dominguez-Gasca, Robert H. Fleming, Andrew Gill, Dominic Kurian, Andrew Law, Heather A. McCormack, David Morrice, Estefania Sanchez-Rodriguez, Alejandro B. Rodriguez-Navarro, Rudolf Preisinger, Matthias Schmutz, Veronica Šmídová, Frances Turner, Peter W. Wilson, Rongyan Zhou, Ian C. Dunn
# Paper abstract #
## Background: ##
Skeletal damage is a challenge for laying hens, as the physiological adaptations for egg laying make them susceptible to osteoporosis. We have shown that genetic factors explain around 40% of variation in end of lay bone quality and a quantitative trait locus (QTL) of large effect was detected on chromosome 1.
## Results: ##
Combining data from the commercial founder white leghorn population and the original F2 mapping population the quantitative trait locus was fine mapped. A number of SNP markers had highly significant associations with tibial breaking strength. The alternative genotypes at the locus had tibial breaking strengths of 200.4 vs 218.1 Newton (p<0.002) and in a subsequent generation the genotype was associated with cortical bone density, and significant effects on the medullary bone. The effects on cortical bone density were confirmed in a further generation where the effect was associated with increased mineralisation maturity of the cortical bone measured by infrared spectrometry and evidence of better collagen cross-linking. The transcriptome of the tibia for each genotype indicated four differentially expressed genes at the locus, one gene, cystathionine beta synthase, having a nine-fold greater expression associated with the allele for low bone quality. The mechanism causing the difference in expression was cis acting and we established that although there was an amino acid difference between alleles, there was no difference in the activity of the enzyme. However plasma homocysteine, the substrate of CBS was greater in the genotype associated with poor bone quality. The effects were associated with increased mineralisation maturity of the cortical bone and evidence of better collagen cross-linking.
## Conclusions: ##
We have defined and validated markers predicting bone strength that can be used in selective breeding. At the same time, we have identified a gene that may give us additional routes to manage bone health in layers over and above genetic selection, whilst identifying how genetic variants affect different aspects of bone turnover shows potential for translational medicine.
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