Then according to Tichý the distance between two constituents (or their associated sets of Q-predicates) is the breadth of the narrowest linkage between them.
Unlike QTL mapping of autosomes and ChrX, it is not possible to associate a narrow linkage peak with a particular trait, since the majority of ChrY does not undergo recombination, thus restricting the linkage unit to the entire non-PAR region of ChrY.
In the present study, by using a high-resolution whole-genome cattle-human comparative map [ 15- 17] and the bovine genome assembly Btau 4.0 (http://www.ncbi.nlm.nih.gov), a total of 15 known genes have been mapped within such narrow linkage region.
We found that the two-SNP haplotype on chromosome 7 showed moderate long-range linkage disequilibrium with a number of SNPs indicating that further information would be required to narrow the linkage peak.
Using this strategy, the confidence intervals of the two major QTLs on the A09 linkage group were narrowed to approximately 1/5 of those in the preliminary linkage mapping (basically, this strategy was used to achieve fine mapping).
These investigations, which will have a much larger sample size of several thousand HD subjects, should clarify the candidate human modifier genes described above, narrow the known linkage peaks, and identify new polymorphisms that exhibit association with age at neurologic onset.
Those regions underlying linkage peaks are narrowed down by fine mapping, so that candidate gene analyses can be pursued.
Orofacial cleft-1 (OMis:119530) is an autosomal disorder where linkage analysis has narrowed the associated gene to a region on 6p24.3 (36).
Recently, Gray-McGuire et al (2010) refined CRC linkage on 9q22 31 and narrowed it down to a 151-kb region using an additional cohort of 69 independent CRC kindred.
Using this strategy, the confidence intervals of the two major QTLs for both SW and SL on the A09 linkage group were successfully narrowed to a large extent, demonstrating the effectiveness of our strategy.
Palmoplantar keratoderma, bothnian type (OMIM 600231) is a rare autosomal-dominant disorder where linkage analysis of patients has narrowed down the associated gene to a region between D12S85 and D12S270 on 12q11-q13 (34).
