LINKAGE OF 4 POLYMORPHISMS ON THE ALPHA(IIB) GENE

The subunits of the platelet integrin alpha(IIb)beta(3) are encoded by two genes located on chromosome 17. Two pathologies are associated wi th structural modifications of I-his complex: Glanzmann's thrombasthen ia and alloimmune thrombocytopenia. The former is a hereditary bleedin g disorder, the latter is due to an immune response linked to the pres ence of specific epitopes defined by single amino acid substitutions c alled human platelet alloantigen (HP;I) systems. Analysing the alpha(I Ib), gene from 112 independent chromosomes, we have defined two new si lent polymorphisms in complete linkage disequilibrium. They are recipr ocally linked to HPA-3 and a previously reported 9 ph deletion in intr on 21, Linkage of these four DNA markers spanning a 5 kb Fragment of g enomic DNA provides a new tool for analysing alpha(IIb) gene pathology and evolution.