Disease and control haplotypes were identified as described in Methods. The mapped markers are SNP 1 (+9 3′ exon 1, C to G), microsatellite 6890, microsatellite 36974, SNP 2 (−9 5′ exon 10, A to T), SNP 3 (+12 3′ exon 10, G to A), and microsatellite 62153. The unmapped markers are microsatellites CA(2), CA(3), and CA(1), in the order they appear on the MSH2 BAC. CA(3) is approximately 20 kb from CA(2), and the set of unmapped markers is thought to be approximately 70 kb upstream from the 5′ end ofMSH2. SNP alleles are coded 1 or 2, with 2 being the less frequent allele. The A→T at nt942+3 mutation lies between the second and third of the mapped markers, at +3 3′ of exon 5. Haplotype reconstruction was not reliable for family England 1, but this family is included in tables 3 and 5.

↵4-150 Reconstructed haplotypes.