Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:Correct control of DNA methylation is vital to normal cellular function, and DNA methylation dysfunction has been linked to a number of human pathologies [18,19], including complex neuropsychiatric phenotypes such as schizophrenia and bipolar disorder [20].
Category: