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:NC is thought to be the result of growth dysregulation affecting the mesodermal portion of the pilosebaceous unit (2), leading to a follicle-based hamartoma with imperfect differentiation in the epithelial portion (4).
Category: