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In genealogy, pedigree collapse describes how reproduction between two individuals who share an ancestor causes the number of distinct ancestors in the family tree of their offspring to be smaller than it could otherwise be. Robert C. Gunderson coined the term; synonyms include implex and the German Ahnenschwund ("loss of ancestors"). [1]
A pedigree chart is a diagram that shows the occurrence of certain traits through different generations of a family, [1] [2] most commonly for humans, show dogs, and race horses. [ citation needed ] Definition
This method of determination requires pedigree checking, however, and establishing a contradiction between phenotype and pedigree is an NP-complete problem. Genetic inconsistencies which do not correspond to this definition are Non-Mendelian Errors.
On a pedigree, polygenic diseases do tend to "run in families", but the inheritance does not fit simple patterns as with Mendelian diseases. This does not mean that the genes cannot eventually be located and studied. There is also a strong environmental component to many of them (e.g., blood pressure). Other such cases include: asthma
Mendelian traits behave according to the model of monogenic or simple gene inheritance in which one gene corresponds to one trait. Discrete traits (as opposed to continuously varying traits such as height) with simple Mendelian inheritance patterns are relatively rare in nature, and many of the clearest examples in humans cause disorders.
Simple pedigree example of sampling bias. Geneticists are limited in how they can obtain data from human populations. As an example, consider a human characteristic. We are interested in deciding if the characteristic is inherited as a simple Mendelian trait.
Family tree showing the relationship of each person to the orange person, including cousins and gene share. A family tree, also called a genealogy or a pedigree chart, is a chart representing family relationships in a conventional tree structure. More detailed family trees, used in medicine and social work, are known as genograms.
In 2000, Family Tree DNA was the first company to provide direct-to-consumer genetic testing for genealogy research. It initially offered eleven-marker Y-chromosome STR tests and HVR1 mitochondrial DNA tests but not multi-generational genealogy tests.