# Genetics Test 2

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1. Not everyone with a disorder has each and every known manifestation of that disorder.
2. End result of Bayesian analysis is a ______
Belief

Several physicians may use the same ovservations to arrive at differing "degrees of belief"; patients want to know if they have a disorder, not our belief system
3. Screening tests shoud have high __________
sensitivity
4. Confirmatory tests should have high ________
specificity
5. A test often dow not prove or rule out the presence of a disorder (it may change the probability)
Informed consent issues
6. Basis of Baye's Theorem:
There is no certainty
7. Bayesian Analysis:
Begin with a model that limits all possibly hypotheses to a constrained subset in the model:  typically two or more ________ hypotheses; each with its own prior probability
Mutually exclusive
8. Probability obtained from the pedigree
Prior Probability
9. Appears normal at age 34, given either genotype (in relation to the problem)
Conditional probabilty
10. How well the test detects affected people.  Formula?
Sensitivity [A/(A+C)]
11. How well the text excludes unaffected people.  Formula?
D/(D+B)
12. How often the test misclassifies affected people as "not affected"?
False-Positive     B/(B+D)
13. How often the test misclassifies affected people as "not affected".  Formula?
False-Negative      C/(A+C)
14. Prevalence formula
(A+C)/(A+B+C+D)
15. If the test result is positive, what's the probability the patient has the disease?
If the test result is normal, what's the probability the patient does not have the disease?
What values help answer the above questions?
Two important questions sensitivity and specificity don't answer.

Predictive Values
16. ____ and _____ are very dependent on the disease prevalence, in addition
PPV and NPV
17. What type of test is used to "rule out" a diagnosis and hsould have a high sensitivity?
Screening test
18. What type of test is used to "rule in" a disease and should have a high specificity?
Confirmatory test
19. Explain to a family that neither a normal or an abnormal test result has 100% predictability.  This should have been explained to the family prior to initiating the consent.  When specifically?
While obtaining informed consent
20. What fraction of offspring from two carrier parents will be unaffected in autosomal recessive traits?
Of the unaffected offspring, 2/3 of the offspring will be heterozygotes.
• 3/4 will be unaffected
• 2/3
21. What is the study of the frequency of alleles and traits in a population; and the study of  the factors that affect gene or genotype frequencies.
Population Genetics
22. What can provide the carrier frequency in a population, making possible genetic counseling about recurrence risks in a kindred?
Population Genetics
23. How many mutations are present for an AR disorder?
How many lethal equivalents?
• 8-10
• 3-5
24. ______ is a fallacy.  We can eliminate all deleterious genes from a population only by eliminating completely that population.
Eugenics
25. Eugenic policies curtail individual freedom, claiming to promote the interest of a future society.
26. Promotes propagation of more "desirable people" types
Positive eugenics
27. Seeks to decrease propagation of more "undesirable people" types
Negative eugenics
28. Improvements in medical management do lead to increased biological fitness of _________
individual patients
29. Hardy-Weinburg Law assumes
• Mating is random and in a large population
• No selection for or against any genotype
• No migration into or out of the population
• No new mutations

(These are never completely met.)
30. Relates the genotype frequencies at a Mendelian locus to the phenotype frequencies in that population.
• Hardy-Weinberg
• p2 + 2pq + a2
• p + q = 1
31. The values of p and q are the same in males and females since we share all X chromosomes.  This is in relation to?

But affected males are more frequent than affected females.
32. Non-random mating (2 examples):
Leads to increased ______
Exposes _______ traits to selection
• 1)  Assortative Mating, 2) Consanguinity and incest
• increased homozygosity
• recessive traits
33. Selection for a similar mate based upon ethnicity, religion, stature, deafness, etc.
Assortative mating
34. Relationship between cloose blood relatives.
Incidence in US?
• Consanguinity
• 2%
35. Risks in offspring:
1st Degree=
2nd Degree=
Third Degree=
• 1st = 50; brother- sister, parent-child
• 2nd= 5-10; uncle-niece
• 3rd= 3-5; first cousins
36. A union between individuals so closely related that the union is illegal.  It is between?
Incest

1st Degree (brother-sister, parent-child)
37. 10-15% of mothers of sporadic cases are
38. What mutations are more frequent among children born of older fathers?
New single gene dominant mutations (apert sydrome, achondroplasa)
39. Acrocephalocyndactyly, craniosyntosis, mid-face hypoplasia, prominence of orbits
Hardy-Weinberg Perturbations
40. An equilibrium may exist between new mutations and selection for or against a mutant allele, tending to maintain allele frequencies constant.
Selection
41.  What disorders are not often recognized because all cases are sporadic.
Autosomal dominant, complete genetic lethal disorders
42. Migration of people changes the allel frequency in a region (ie. hispanics into USA)
Gene flow
43. Small "isolated" population effects
Genetic Drift
44. Allele frequency can occur in small populations by chance.
• Random fluctuation
•     Leads to extinction, fixation, and the founder effect on some alleles.
45. A case of genetic drift in which a small founder population with limited genetic variation derives from a larger population, resulting in a large change in allele frequencies.
Founder Effect
 Author: BrookeNH10 ID: 181004 Card Set: Genetics Test 2 Updated: 2012-10-31 23:52:39 Tags: Bayesian Hardy Weinberg Folders: Description: Bayesian, Hardy-Weinberg Show Answers: