Although association with several single nucleotide polymorphisms (SNPs) has been demonstrated, none have proven causative.
For instance, intensive feeding and hard floor surfaces are proven causative factors of laminitis [ 4, 17, 18, 24], and abrupt changes to these conditions in connection with calving further increase the risk of laminitis-related claw horn lesions [ 31, 32].
Although no proven causative mutations have been described to date (61), a polymorphism influencing the methylation of TRPC3 was reported in idiopathic ataxia, although its frequency did not reach the significance in the population analysed (62).
Although the presence of S. pneumoniae in the nasopharynx during pneumonia does not prove its causative role, a pneumococcal disease is likely to be caused by the serotype present in the nasopharynx.
In order to prove a causative role, it will be important to define the molecular mechanisms through which cadmium in low exposure can cause adverse health effects.
Rather than following the natural course of gene expression changes, transgene-controlled β2-subunit overexpression should prove its causative role in native tissue.
We note that our data are correlative but, as yet, cannot prove a causative influence of daf-16 expression level on these phenotypes in the gonochoristic species.
Moreover, the ecological study design cannot prove a causative relationship between the two factors.
These putative resistance genes can be used as targets for future genetic and functional studies to prove a causative link with resistance to IBV.
However, because of the uncontrolled design, our study cannot prove a causative relationship between the observed hemodynamic changes and metoprolol therapy.
