PTPN1 and type 2 diabetes mellitus: Fourteen PTPN1 SNPs were selected for the study, including: (i) six common PTPN1 gene promoter or intronic SNPs (-7077G/C, rs941798, rs1570179, rs3787345, rs754118 and rs718050) showing association with T2D in previous studies [14,15,27]; (ii) seven tag SNPs selected from the HapMap version 14 of January 2005; and (iii) the synonymous exon 8 variant rs2282146, previously referred to as P303P [28].