Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Pedigree Charts The family tree of genetics Overview I. What is a pedigree? a. b. II. Constructing a pedigree a. b. III. Definition Uses Symbols Connecting the symbols Interpreting a pedigree What is a Pedigree? A pedigree is a chart of the genetic history of family over several generations for a particular trait. Can be used: – to discover the inheritnace pattern of a disease or disorder (autosomal versus sex-linked, dominant vs. recessive) – Along with punnett squares to determine genotype and phenotypes probabilities Constructing a Pedigree Gender symbols Female Male Connecting Pedigree Symbols Married couple (or parents of a child) Siblings Connecting Pedigree Symbols Twins: Fraternal twins (do not have identical DNA) Identical twins (DO have identical DNA) Example Example pedigree chart (blank) Symbols in a Pedigree Chart Affected X-linked carrier Autosomal carrier Deceased Interpreting a Pedigree Chart 1. Determining if the pedigree chart shows an autosomal or X-linked disorder/ disease X-linked disorders occur on the X chromosome (remember males have only 1 X chromosome) Autosomal disorders occur on the other chromosomes (pairs 1-22) Therefore… If more of the males in the pedigree are affected the disorder is Xlinked If there is not a significant difference in # of males and females the disorder is autosomal. Example of Pedigree Charts Example A: Autosomal or X-linked? Answer Autosomal Interpreting a Pedigree Chart 2. Determining whether the disorder is dominant or recessive – If the disorder is dominant, one of the parents of an affected individual must have the disorder. – If the disorder is recessive, neither parent has to have the disorder because they can be heterozygous (carriers). Example B Dominant or Recessive? Answer Dominant Example C Dominant or Recessive? Answer Recessive Summary Pedigrees are family trees that illustrate genetic history. To begin to interpret a pedigree, determine if the inheritance pattern of the disorder/disease (autosomal or X-linked & dominant or recessive) Pedigrees can be used to find out the probability of a child having a disorder in a particular family.