Andrew Yee
ASCI 304
Dan Peterson
May 24, 2014
Journal Article Assignment
1. The objective of the authors is to identify the source of hip dysplasia in canines by using
genetic mapping to identify both quantitative trait locus and markers on chromosomes
(microsatellites) that are related to the cause of hip dysplasia in a sample size of 192
Labradors that are polymorphic of the trait.
2. In comparison to the author’s study, the most ideal mapping would require large
populations of the individuals that are polymorphic of the specific trait that is being
observed, the subjects of the population must be very related and span multiple
generations. The author’s study of Labrador retrievers consisted of a population of 192
which satisfies having a large population. Additionally, there were two strains that were
present; one that had the maximum occurrences of hip dysplasia and one that had low
occurrences of hip dysplasia which provides polymorphic variation of the trait. Some of
the susceptible Labradors retrievers were bred to Greyhounds to provide a pedigree of 7
generations which fulfills the “span multiple generations” requirement. The study sample
provided satisfies the requirements for an ideal mapping population.
3. As for markers, the ideal markers within a study must be numerous, polymorphic (minor
allele frequency greater than .1), span an entire genome without gaps, and close enough
to one another to show linkages (less than 30 centimorgans). Specifically in this study,
microsatellite markers were used and both 249 and 323 microsatellite markers were
selected. 276 of the markers turned out to have a allele frequency of over .1, the average
being .6 although there were a large range of values. These microsatellites did in fact
span the entire genome with the majority of the markers showing linkages with one
another. Only several of the chromosomes were over 10 centimorgans and the average
distance between the rest of them was 9.1 centimorgans.
4. The genetic basis of canine hip dysplasia lies on quantitative trait loci where several
not, then you would know that not all the QTLs found on those chromosomes on the first
sample lead to the influence of hip dysplasia.