Location: Animal Disease ResearchTitle: Association analysis of variant near ZNF389 with ewe cumulative production in three sheep breeds ) Author
|Highland, Margaret - Maggie|
|Taylor, Joshua - Bret|
|Knowles, Donald - Don|
Submitted to: Animal Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 3/3/2014
Publication Date: 8/1/2014
Citation: White, S.N., Mousel, M.R., Gonzalez, M.V., Highland, M.A., Herrmann-Hoesing, L.M., Taylor, J.B., Knowles Jr, D.P. 2014. Association analysis of variant near ZNF389 with ewe cumulative production in three sheep breeds. Animal Genetics. 5(4):613-614. Interpretive Summary: Ovine progressive pneumonia virus (OPPV) infects 24% of U.S. sheep and causes pneumonia, mastitis, and body condition wasting. There is no vaccine and no cure for OPPV, but selective breeding of sheep with greater ability to control OPPV has promise to reduce disease. A recent study identified a small deletion variant near the ZNF389 gene as the first genetic marker for post-infection control of OPPV with consistent evidence from multiple sheep flocks. An important question is whether use of this genetic marker to breed sheep with better ability to control OPPV will help or harm ewe production by standard measures. To address this question, we tested association between the marker near ZNF389 and 13 standard measures of ewe lifetime production in 1,279 ewes. Measures included birth weight, weaning weight, mature weights at 3 and 4 years, milk score, udder scores at 3 and 4 years, and lifetime measures of: fleece weight, number of lambs born, number of lambs born alive versus dead, weight of lambs born, and weight of lambs weaned. There was no statistically significant association with any of these traits. A trend toward lighter birth weights was observed, but it was not statistically significant and there was not even a trend toward association with weights at older ages. These data suggest that genetic selection for better ability to control OPPV using the genetic marker near ZNF389 will not harm average sheep production represented by these standard measures.
Technical Abstract: Description: Genome-wide association identified a gene region including ZNF389 as highly associated with small ruminant lentivirus (SRLV) proviral concentration among infected sheep. Within this region, a deletion variant near ZNF389 was associated with control of SRLV proviral concentration in multiple sheep flocks. Since proviral concentration is a measure of proviral replication that has also been correlated with disease, this deletion variant may be predictive for SRLV disease severity. However, an open question is whether this deletion variant could also be associated with production or other traits that might enhance or detract from its value in selective sheep breeding. Methods: A total of 1,279 Idaho Rambouillet, Polypay, and Columbia ewes with production records were sampled in 2004 and 2008 as previously described. Phenotypes included birth weight, weaning weight, mature weights at 3 and 4 years, milk score, udder scores at 3 and 4 years, and lifetime measures of: fleece weight, number of lambs born, number born alive, number born dead, weight of lambs born, and weight of lambs weaned. Conclusions: The ZNF389 deletion variant was not associated with any tested production traits after multiple testing corrections. The insertion homozygote genotype previously associated with reduced SRLV proviral concentration was associated nominally with lower birth weight, but the weight difference was small and not significant after multiple testing correction (P>0.15). Further, there was no association with weaning or later weights. These results show no association of the ZNF389 deletion variant with ewe lifetime production. However, additional traits should be examined to more fully assess this locus.