A pedigree is a chart of the genetic history of a family over several generations

• Males are represented as squares, while females are represented as circles
  

• Shaded symbols mean an individual is affected by a condition, while an unshaded symbol means they are unaffected
  

• Generations are labeled with roman numerals and individuals are numbered according to age (oldest on the left)
  

• A horizontal line between man and woman represents mating and resulting children are shown as offshoots to this line
  

  • Note: Unions between close relatives is typically discouraged because inbreeding reduces genetic diversity and increases the possibility of inheriting recessive disease conditions
    

Autosomal Inheritance

Autosomal conditions refer to any genetic disorders caused by mutations to genes on any of the first 22 homologous pairs of chromosomes

• Dominant and recessive disease conditions may be identified only if certain patterns occur (otherwise it cannot be confirmed)
  

Autosomal Dominant

• If both parents are affected and an offspring is unaffected, the trait must be dominant (parents are both heterozygous)
  

• All affected individuals must have at least one affected parent
  

• If both parents are unaffected, all offspring must be unaffected (homozygous recessive)
  

Autosomal Recessive

• If both parents are unaffected and an offspring is affected, the trait must be recessive (parents are heterozygous carriers)
  

• If both parents show a trait, all offspring must also exhibit the trait (homozygous recessive)