Association:1. In the field of dysmorphology, which focuses on birth defects, an association refers to the repeated occurrence of a set of multiple anomalies in two or more individuals. These anomalies do not fit the criteria of a known syndrome, like Down syndrome, nor do they represent a sequence of malformations or a polytopic field defect, where defects are localized to a specific body area. An example of such an association is the presence of certain birth defects.2. More generally, an association is when two or more traits appear together more frequently than would be expected by random chance. A notable example of this is in the context of white blood cells, where a specific feature known as HLA (human leukocyte antigen) is involved. A particular HLA type, B-27, is linked to an increased likelihood of several diseases. The strength of this association is significant; for instance, the likelihood of one particular disease occurring is 87 times greater in individuals with HLA B-27 compared to the general population.
