RESUMO
<p><b>OBJECTIVE</b>To explore the role of the mutation of presenilin-1 exon 6 in pathogenesis of Alzheimer's disease(AD) patients.</p><p><b>METHODS</b>Exon 6 of presenilin-1 was analyzed by use of polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) and DNA analyzer technique in 2 patients with familial AD, 53 patients with sporadic DA, 60 patients with vascular dementia(VD) and 90 normal controls.</p><p><b>RESULTS</b>Mobility shift of SSCP in exon 6 of presenilin-1 was detected in 2 cases with FAD, 4 cases with SDA and 1 case with VD. Two missense mutations were found in the patients by DNA sequence analysis, one mutation was 1123 nt C-->G(Cys 23 Trp) and the other was 1300 nt A-->C(Asp 200 Ala).</p><p><b>CONCLUSION</b>Mutations in exon 6 of presenilin-1 existed in the patients with FAD and SDA, and the two missense mutations were probably pathological by nature.</p>