Update on a linkage trend between schizophrenia (SZ) and the 11q21-22 region in pedigrees of Eastern Quebec

At the 1993 meeting of the ASHG, we presented preliminary results on the observation of a linkage trend (Z{sub max} = 2.69) using a recessive model in one large pedigree (255) from Eastern Quebec showing 10 individuals affected by SZ. Our sample is still in progress and we now present additional results after (1) extending pedigree 255 (adding a few genotypes and phenotypes that were unknown in 1993); (2) genotyping 10 new markers in the 11q21-22 region; (3) performing three-point analyses and (4) adding two new SZ pedigrees to our initial sample of four. Results: The extension of pedigree 255 now yields a maximum lod score of 3.06 with marker D11S35. The maximum lod score is still observed at D11S35 after genotyping 10 other markers including INT-2, DRD2 and CD3D. Lod scores greater than 1.5 are also observed with markers D11D901, D11S876 and D11S919 in family 255. Three-point and two-point analyses yielded consistent results. The maximum lod scores were comparable and they were all observed in the close vicinity of D11S35. A maximum lod score of 1.35 was obtained in one of the two new SZ pedigrees. The heterogeneity analysis of the total sample of 6 SZ pedigrees, using HOMOG,more » favored the hypothesis of linkage under heterogeneity 1284 to 1 (Z=3.11).« less