Recessive- An allele that is not phenotypically expressed when its counterpart is dominant. Dominant- Refers to an allele that is expressed phenotypically and masks any recessive counterpart. X-linked gene- a gene found on a chromosome designated as a sex chromosome (X or Y).
If most of the males in the pedigree are affected the disorder is X-linked If it is a 50/50 ratio between men and women the disorder is autosomal.
Interpreting a Pedigree Chart Determine if the pedigree chart shows an autosomal or X-linked disease. Symbols in a Pedigree Chart Affected X-linked Autosomal carrier Deceased Ĭonnecting Pedigree Symbols Fraternal twins Identical twins Examples of connected symbols:Ĭonnecting Pedigree Symbols Married Couple Siblings Examples of connected symbols:Įxample What does a pedigree chart look like?
Scientists or a genetic counselor would find out about your family history and make this chart to analyze. What is a Pedigree? A pedigree is a chart of the genetic history of family over several generations. Overview What is a pedigree? Definition Uses Constructing a pedigree Symbols Connecting the symbols Interpreting a pedigree Pedigree Charts The family tree of genetics