Attempt

What is Hardy-Weinberg Equilibrium?

  • p^2 + 2pq + q^2 = 1
  • all the alleles in the population = 1

What are the 3 possible interpretations of a paternity test?

  • Exclusion - profiles are too different to be considered related
  • Inconclusive - insufficient data or ambiguous results
  • Cannot exclude or is not excluded - results are similar enough to have originated from related individuals

What is Paternity Index?

  • the probability of the child the mother and the alleged father vs a random individual
  • The likelihood ratio that ‘not excluded’ results are indeed related
  • PI = LR = Pr (child | mother and alleged father)

Pr (child | mother and random man)

Essen Moller Formula

Pr( AT| M&C) = Pr (AT and M&C)/Pr(M&C)

  • M&C - mother and child

  • Theta differentiates is it identical in state or identical by descent

    • theta connection between siblings on average is .5
    • .03 or .01 is used for measuring a match to a match

Identical in State VS Identical by Descent

  • Identical in State - The same alleles occurring in two individuals by chance.
  • IBD - Two individuals are related and thus carry the same allele.

What is a Likelihood Ratio?

  • Comparison of 2 explanations for data

e.g. Man and child both have Q allele can be due to either:

  • Paternity
  • Non-paternity and lots of coincidence

LR = (1/4) / (1/2q)

RMNE means Random Man Not Excluded

STR Mutations

How often do STR mutations occur?

  • usually 1 in 1000 meioses

Which is higher, Maternal or Paternal?

  • Paternal
  • females less likely to have mutations as it is already made up, males make thousands of oocytes and therefore are more likely to have a mutation occur.

Which STR loci have the highest levels?

  • VWA
  • FGA
  • D18S51

Which STR loci have the lowest levels?

  • TH01
  • TPOX
  • D16S539

What is Probability of Paternity?

  • POP = (CPI/ CP1 +1)*100
  • CPI = Combined Paternity Index

What is Prior Probability?

  • estimate of probability before considering genetic evidence

  • What does 50% Prior Probability mean?

    • plaintiff and defence have equal likelihood of being plausible

Avuncular VS Paternity

  • avunculus = uncle
  • paternal = father