In conclusion, the present study represents, to the best of our knowledge, the first study based on both case-control and familiar data sets, showing the joint effect of HLA, INS and PTPN22 in T1D in a Caucasian population with a wide range of age at T1D onset, generalizing previous findings regarding data sets consisting of patients and controls <15 years by Bjørnvold M. et al. [34]. The gene discussed is PTPN22; the disease is type 1 diabetes mellitus.