Pedigrees

• A pedigree is a diagram of family relationships that uses symbols to represent people and lines to represent genetic relationships. These diagrams make it easier to visualize relationships within families, especially large extended families.

• Pedigrees are often used to determine the mode of inheritance (dominant, recessive) of genetic diseases.

• Squares represent males.• Circles represent females.• Horizontal lines linking a • male and female represent• mating. Vertical lines • extending downward from • a couple represent their children.

•What is a Pedigree?

• If the purpose of a pedigree is to analyze the pattern of inheritance of a particular trait, it is usual to shade in this trait.

• Infected male

In this pedigree: the grandparentshad three children, two boys andone girl. The daughter married and Produced two grandchildren, bothboys.The grandfather has the trait. The daughter is a carrier. One of the grandsons has the trait.

• There are four types of inheritance patterns that we will be analyzing:

• 1. autosomal dominant• 2. autosomal recessive• 3. X – linked dominant• 4. X- linked recessive

•Types of Inheritance

• A – has the trait• a – normal (no trait, recessive)

•Autosomal Recessive• A – normal ( no trait, recessive)• a – has the trait

•Autosomal Dominant

•X – Linked Dominant• XA – has the trait• Xa – normal• Y – Y chromosome (males only)

•X – Linked Recessive• XA – normal• Xa – has the trait• Y – Y chromosome (males only)

• The location of a gene.

• For example, the locus of the gene OCA1 (or Oculocutaneous Albanism Type 1, the gene associated with albinism) is on 11q1.4-2.1, which means it is on the long arm of chromosome 11, between sub-band 4 of band 1 to sub-band 1 of band 2.

•Locus