Disagreement of ontologies. In the MPO, abnormal ion homeostasis and abnormal copper homeostasis are not connected by an ancestor/descendent relation. The results of analysis by GULO of logical definitions of the MPO terms suggests that abnormal copper homeostasis should be a subclass of abnormal ion homeostasis, because the term copper ion homeostasis is a descendant of ion homeostasis in the GO. These two terms are used to logically define the corresponding terms in the MPO.
Köhler et al. BMC Bioinformatics 2011 12:418 doi:10.1186/1471-2105-12-418