The most promising chromosomal region was 18q12.1-21.33, where the highest two-point LOD score of 3.45 (θ = 0.04) was obtained, with marker
D18S468 assuming the dominant mode of inheritance. Four markers surrounding the best marker exceeded a pair-wise LOD score of 1.0;
D18S1135 (
Z max dom = 1.39, θ = 0.14, α = 1.00),
D18S450 (
Z max dom = 1.49, θ = 0.08, α = 1.00),
D18S64 (
Z max dom = 1.70, θ = 0.08, α = 0.84), and
D18S1147 (
Z max dom = 1.68, θ = 0.12, α = 0.83) spanning an area of ∼30 cM. One allele on the best marker
D18S468 was more often present (37%) in affected than in unaffected (26%) family members, and another allele was found more often in unaffected (34%) than in affected (25%) subjects. Three-point analysis in the best region using adjacent markers
D18S1102–
D18S468,
D18S468–
D18S1143, and
D18S1143–
D18S450 produced maximum multipoint LOD scores of 1.85 (θ = 0.03; 0.10), 2.28 (θ = 0.08; 0.05), and 1.73 (θ =0.15; 0.03), respectively. When we combined the information from markers
D181135 and
D18S468, located 5 cM apart, the maximum three-point LOD score was 2.80 (θ = 0.05; 0.10), and using markers
D18S468 and
D18S450, located 8 cM apart, the highest three-point LOD score of 4.33 (θ = 0.05; 0.08) was obtained. The complete results for three-point analysis over the region are shown in
Table 3 .