Linkage studies are good for localising areas of disease risk across the genome. They can also be used to study multiple genetic markers simultaneously. There are however several disadvantages to linkage studies. Researchers need to identify a large number of families with several affected generations. If the disease is of late-onset with a high mortality, finding families with more than one affected generation will be difficult. Linkage studies are less helpful for complex traits, such as diabetes where multiple genes are important in disease causation.
Gasser and colleages* studied several families who had multiple members affected with Parkinson’s disease. The purpose of this study was to find a genetic marker that increased susceptibility to the condition. Two families that were thought to show the greatest potential for linkage underwent genome wide scans and were found to have several markers on chromosome 2p that were inherited with the condition. This area was more closely investigated by the researchers, using the remaining families, and the researchers found the most likely location of the locus was 2p13.
*Gasser T, Müller-Myhsok B, Wszolek ZK, Oehlmann R, Calne DB, Bonifati V, Bereznai B, Fabrizio E, Vieregge P, Horstmann RD. A susceptibility locus for Parkinson's disease maps to chromosome 2p13. Nat Genet. 1998 Mar;18(3):262-5.
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