Inheritance Patterns Flashcards
What is the symbol for a male on a pedigree?
→ A square
What is the symbol for a female on a pedigree?
→ A circle
How do you show that two people are partners on a pedigree?
→ There is a line between them
How do you show children on a pedigree?
→ There is a line down
How do you show siblings on a pedigree?
→ There is a line above connecting them from the top
How do you show affected people on a pedigree?
→ They are colored in
How do you show carriers on a pedigree?
→ A shaded dot within the shape
How do you show a consanguineous couple on a pedigree?
→ A double line joining them
What is a stillborn baby of unknown sex on a pedigree?
→ A rhombus with the SB symbol
How is a spontaneous abortion shown on a pedigree?
→ a triangle
How is a therapeutic abortion shown on a pedigree?
→ A triangle with a line through it diagonally
How are twins shown on a pedigree?
→ two shapes coming from the same vertical line
How is pregnancy shown on a pedigree?
→ A rhombus with a P inside it
What is a rhombus on a pedigree?
→ Unaffected person whose sex is unknown
How do autosomal dominant conditions manifest?
→ Heterozygous form
What are the 4 key things to look for in an autosomal dominant pedigree?
→ Multiple generations affected
→ Both sexes
→ Male to female and female to male transmission
→ Most will have an affected parent
How do you know that an autosomal dominant condition is not carried on the sex chromosome?
→ Both genders are affected
→ Transmission between sexes
What is the risk for each child of an affected parent with an autosomal dominant condition?
→ 50% risk
What is penetrance?
→ % of individuals who carry the mutation and develop symptoms of the disorder
What does a 75% penetrance mean?
→ Someone can have the dominant allele but not phenotypically have the disease
→ Huntingtons
What is variable expressivity?
→ Variation in the severity/symptoms of the disorder