gntcs Flashcards
unfilled square
male unaffected
unfilled circle
Female (unaffected)
how are affected shown
shaded in black
carriers of autosomal
half shaded
carriers of x linked (only females are linked carriers)
⦿ (circle with black dot)
deceased
circle/square with line through it diagonally
proband
first person seeking medical attention
c/s with a small arrow pointing towards the bottom left corner
how are Monozygotic (identical) twins shown
2 branches from same point with a horizontal line through it
Dizygotic (non-identical) twins
come from same point with 2 branches but no horixontal line
Consanguineous Couple
linked by 2 horizontal lines
how to draw a pedigree diagram
Start at the bottom with the proband and siblings
Choose one parent ask about their siblings, children and parents
Add other side of family
Ask about children of other partners
complicating factors with ad
Age of onset
Some diseases develop with age due to accumulation of damage,
in exams they’ll miss people who aren’t old enough
what is risk
and how to work it out
This is a calculation of the predicated chance of having the disease or being carrier.
Work from person with
known phenotype to subject (closest relative on each side of family)
Multiply risks together
ethnic background and inheritance
Heterozygote advantage- sickle cell, CF?
Founder effect- Tay-Sachs
what is population risk
not because of genetic or family
same as the risk for anyone
