In a study with 1472 participants, serum macrophage inhibitory cytokine 1 (MIC-1) concentrations were found to be increased in the majority of patients with PC, even in those with early-stage disease and negative for CA19-9, suggesting a role for MIC-1 as a biomarker for PC diagnosis and follow-up [50]. The gene discussed is GDF15; the disease is pachyonychia congenita.