Pedigrees

For this section you should understand:

• Pedigree symbols


• Labeling a pedigree


• Decisive patterns


• Probability and pedigrees

Pedigrees are organized family histories and they can be used to analyze the genetics of a trait in a manner similar to what we do with crosses. Pedigree analysis is particularly useful for single gene defects such as "inborn errors of metabolism" (e.g., albinism, cystic fibrosis, etc.) with discrete phenotypes. More complex genetic diseases (e.g., risk of heart disease and left-handedness) do not give clear inheritance patterns in pedigree analysis and so we will not consider them here. Pedigree analysis can also be confounded whenever the environment plays a significant role in determining the phenotype or if more than one gene is involved, so we will ignore these factors at this introductory level.