Objective: To more finely linkage-map primary osteoarthritis (OA) susceptibility loci on chromosomes 4 and 16.
Methods: Two hundred eighteen families, each with 2 or more women concordant for primary OA (ascertained by total hip replacement [THR] or total knee replacement), were genotyped using highly polymorphic microsatellite markers from chromosomes 4 and 16, at an average density of 1 marker every 4 cM. Two-point and multipoint linkage analyses were performed for all 218 families and for the 146 families from the 218 that included women concordant for THR (female-THR families).
Results: A single region of linkage was identified on chromosome 4q, with a maximum multipoint logarithm of odds (LOD) score (MLS) of 3.1 in the 146 female-THR families. This locus was centered 79 cM from the 4p telomere and had a 1-LOD support interval of 4 cM. Two regions of linkage were identified on chromosome 16, the first on 16p with an MLS of 1.7 in the female-THR families and the second on 16q with an MLS of 1.9 in all 218 families. The first locus was centered 46 cM and the second 89 cM from the p-telomere. The 1-LOD support intervals were 12 cM and 10 cM, respectively.
Conclusion: Finer linkage mapping using a high density of microsatellite markers has narrowed female OA susceptibility loci on chromosomes 4 and 16. The regions have been narrowed sufficiently for association analysis.