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Several polymorphisms in the insulin receptor substrate-1 (IRS1) gene have been reported in the last years. The most common IRS1 variant, a Gly VArg substitution at codon 972 (Arg972 IRS1), is more prev- alent among subjects who have features of insulin resistance syndrome asso- ciated, or not, with type 2 diabetes in European populations. To determine whether the absence of IRS1 polymorphism is a more general characteristic of Paleo-Indian-derived populations, we examined the Arg972 IRS1 poly- morphism in Parakana ̃ Indians and found a lack of this polymorphism in the Parakana ̃ population.