Pedigree
Using a pedigree to track a genetic trait.
Using a pedigree to track a genetic trait.
1/ The pedigree is a diagram that is used to track a trait across a family tree. It might be cool to track the trait of red hair in your family, the pedigree is critical for tracking a genetic disease through a family to determine the risk of inheritance.
2/ There are some basics to drawing a pedigree. The lines connect lineages with the males being the squares and the females being the circles. The roman numerals on the left mark each generation.
3/ Some pedigrees will use a slash / to cross out deceased people in the pedigree. There are some basics to drawing a pedigree.
4/ Anyone who has the trait gets a small colored circle in the center. They carry the gene for the disease, but they are not affected. Those that have the actual disease get fully colored in.
5/ The lines show the children from each generation and their mates. The children for each set of parents gets listed from left to right in the order of birth.
6/ By looking at the patterns of inheritance on a pedigree, we can quickly see how the trait is passed. If the trait affects both males and females, its an autosomal trait. If it only affects males or females, then its a sex linked disease.
7/ If the disease affects every generation, it is a dominant trait. An autosomal dominant trait will affect about 50% of both males and females from an affected parent who is heterozygous.
8/ Recessive traits tend to skip generations and can often skip several generations as many parents get the trait, but not the full disease. From the chart above, we can quickly see this represents a trait that is autosomal dominant.
9/ The pedigree is a great tool for genetics to track a trait across generations to get valuable insight into how its passed from one generation to the next.
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