SORCS2 and periodontal disorder: Our study found a previously unrecognized role for the proBDNF-SorCS2 axis as a critical negative regulator of periodontal homeostasis.5, 6, 7 While the neurotrophic functions of mature BDNF in oral biology are well documented, its precursor, proBDNF, has remained largely unexplored in periodontal disease.