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Understanding Pedigree Analysis Symbols and Traits Inheritance

Pedigree charts show family records, useful for studying genetic conditions in humans & animals over generations. Symbols represent male, female, carriers, affected, normal family members. Learn about dominant and recessive trait inheritance in pedigrees. Explore how the inheritance of rare traits like woolly hair and disorders such as albinism unfolds through generations. Dive into sex-linked diseases like hemophilia in royal families analyzed through pedigrees.

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Understanding Pedigree Analysis Symbols and Traits Inheritance

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  1. Pedigrees • Pedigree charts show a record of the family of an individual. • It can be used to study the transmission of a hereditary condition (genetic disease). • It is particularly useful when there are large families and a good family record over several generations. • Used in humans & animals.

  2. I, II, III 1, 2, 3 Children (in birth order) Non-identical twins Carrier (heterozygote) Died in infancy Generations Affected male Identical twins Normal male Affected female Normal female Sex unknown Pedigree Analysis Symbols are used to represent males, females etc. For traits of interest, symbols can be shaded to indicate individuals carrying the trait. Individuals are designated by their generation number and then their order number in that generation.

  3. Pedigree Charts:

  4. Pedigree Chart Symbols Males, Females, married, children, siblings, affected, normal Carrier (heterozygote)

  5. Inheritance of Dominant Traits • In the inheritance of autosomal dominant traits, each affected individual will have at least one parent who is also affected. • If large number sof families are examined equal numbers of males and females are affected. • Inheritance of the rare trait woollyhair in humans follows this pattern. • In the 1st generation, female I-2is heterozygous for a woolly hairallele. • Half of her offspring are alsoheterozygous for the woolly hairallele, where t is expressed. The the rest (II-5, II-6, II-7) arehomozygous recessive andhave normal hair.

  6. Inheritance of Recessive Traits • The pedigree for albinism (lack of pigment in the hair, skin and eyes) is inherited as an autosomal recessive trait. • The trait is not sex linked and is shown by both males and females. The affected female in the third generation has phenotypically normal parents. • All generation II offspringare carriers for the albinoallele. • III-2 is an albino girl whosepaternal grandmother andmaternal grandfather arealso albinos. • All her other relatives are phenotypically normal.

  7. Is this a recessive or dominant disease?

  8. Sex Linked Hemophilia In the Royal Family

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