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23 Cards in this Set
- Front
- Back
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Nonsense mutation |
Some point mutations change a codon to a stop codon |
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Consequences of nonsense |
1. Introduce a premature termination codon 2. Nearly complete protein with reduced activity 3. Dramatically shortened protein with no activity 4. Shortened protein that interferes with activity |
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Disorder caused by nonsense mutations |
Beta thalassemia dominant inclusion body type Severe AD |
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Point mutations |
Base substitutions in which one base pair is altered |
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Silent mutations |
Change a nucleotide without changing the amino acid |
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Missense mutations |
Change an amino acid, which may or may not affect protein function |
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Types of point mutations |
Transition: a pyrimidine replaces a pyrimidine; a purine replaces a purine Transversion : a purine and a pyrimidine are interchanged |
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In frame or out of frame deletion |
Affect the way the codons are read. Normal: the car saw the dog In frame: the dog Out of frame: the car awt hed og |
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Example of in frame del and out of frame del |
DMD VS BMD gene: dystrophin DMD: out of frame BMD: in frame |
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Triple nucleotides disorders |
Fragile x: CGG, maternally expanded, <44, 45-54, 55-199, >200, loss of function of FMRP Huntington: CAG, paternally expanded, <26, 27-35, 36-39,>49. 36-55 adult onset. >60 juvenile onset-HDD Myotonic dystrophy1:CTG,<34, 35-49, >50-DMPK Myotonic dystrophy 2: CCTG,<26, 27-74, >75-CNBP Friedreich ataxia: GAA, <33, 34-65, >66-FXN-only AR |
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Sensitivity |
If a person has a disease, how often will the test be positive? Highly sensitive tests means a negative result is very likely to be real =true positive/(true positive + false negative) |
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Specificity |
If a person does not have a disease, how often will the test be negative Highly specific tests means a positive result is very likely to be real. =true negatives/(true negative+false positive) |
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Positive predictive value |
if the test result is positive, how likely is it that the person has the disease =true positive/(true positive+false positive) |
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Negative predictive value |
if the test result is negative, how likely is it that the person does not have the disease =true negative/(true negative+false negative) |
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Analytic validity |
If a lab receives a sample with a particular mutation, how likely is it that it will report a positive result? Looking for sensitivity and specifity |
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Clinical validity |
If a mutation is found by a test, can you predict a phenotype or syndrome? PPV and NPV Limited by genetic heterogeneity and incomplete penetrance |
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Clinic utility |
If you know the genotype, can you affect a patient's health? How useful is this test for my patient |
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clinical lab vs research lab |
clinical lab is CLIA certified research lab and labs outside the USA are not CLIA certified |
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CLIA |
clinical laboratory improvement amendments part of Centers for Medicare and Medicaid Services (CMS) |
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How to detect del/dup |
southern blots RT-PCR MLPA microarray |
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Prader-Willi syndrome |
maternal UPD |
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Angelman syndrome |
Paternal UPD |
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Triple nucleotides disorders |
Fragile x: CGG, maternally expanded, <44, 45-54, 55-199, >200, loss of function of FMRP Huntington: CAG, paternally expanded, <26, 27-35, 36-39,>49. 36-55 adult onset. >60 juvenile onset Myotonic dystrophy1:CTG, Myotonic dystrophy 2: CCTG, Friedreich ataxia: GAA |
