PCR strategy for the elucidation of the GPIa gene surrounding the polymorphic base at position 2531 (arrow). Genomic DNA was amplified by PCR using primer pairs P61, P42 and P6, P7. PCR products were sequenced for the determination of exon-intron boundaries. The polymorphic exon 20 (bases 2478-2619) encoding the amino acids Glu₇₈₂-Pro₈₂₈ is flanked by 2 introns (421 and 1,200 bp) of phases 2 and 0 (italic). For genotyping analysis of the polymorphic bases 2531 and 2532 (bold), a 630-bp fragment was amplified using primer pair P61, P83.