in Hispanic Americans The Insulin Resistance Atherosclerosis Study (IRAS) Family Study

Protein tyrosine phosphatase (PTP)-1B, encoded by the PTPN1 gene, catalyzes the dephosphorylation of pro-teins at tyrosyl residues. PTP-1B has been implicated in negatively regulating insulin signaling by dephosphory-lating the phosphotyrosine residues of the insulin re-ceptor. The genetic contribution of PTPN1 to measures of glucose homeostasis has been assessed in 811 His-panic subjects from the Insulin Resistance Atheroscle-rosis Study Family Study (IRASFS). Thirty-five single nucleotide polymorphisms (SNPs) spanning 161 kb and containing the PTPN1 gene were genotyped and tested for association. All 20 SNPs with minor allele frequen-cies>0.1 in a single haplotype block covering the PTPN1 genomic sequence show significant association with the insulin sensitivity index (Si) (P 0.044