Yc. Huang et Rd. Shanks, VISUALIZATION OF INHERITANCE PATTERNS FROM GRAPHIC REPRESENTATION OF ADDITIVE AND DOMINANCE RELATIONSHIPS BETWEEN ANIMALS, Journal of dairy science, 78(12), 1995, pp. 2877-2883
Evaluation of pedigrees of normal and affected individuals help to sug
gest possible patterns of inheritance. Because large numbers of indivi
duals are involved in studies of genetic disease, classic two-dimensio
nal family tree charts are difficult to draw. Instead, DFA plots of gr
aduated circles, weighted by dominance relationships, inbreeding, and
additive relationships between individuals can be plotted above, on, a
nd below the diagonal. Base animals without phenotypic measurements co
ntribute information for computation of approximate dominance relation
ships, inbreeding, and additive relationships, but are not explicitly
in the graph. Plotting only a set of randomly selected animals for eac
h combination of phenotypes improves the visualization effect, especia
lly when pedigrees are large or when computer resources are limited. F
or deficiency of uridine monophosphate synthase and interdigital hyper
plasia, DFA plots showed higher densities of additive and dominance re
lationships among affected animals. However, DFA plots did not show cl
ear patterns of inheritance for heel erosion, laminitis, or sole ulcer
s because environmental effects were important for those traits. Group
ed graduated circles also improved visualization. The function of DFA
plots is comparable with statistical scatter plots that display data t
o help examine statistical approaches. The DFA plots serve as a first
approach to evaluate genetic hypotheses before a more complex model is
fit.