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36 Cards in this Set

  • Front
  • Back
Prenatal diagnosis sources
2) chorionic villus samples (CVS)
3) embryonic blastomeres for preimplantation diagnosis (single cell PCR)
4) Fetal cells in maternal blood
Collection for genetic testing
any cell in human body
Clinical purposes of molecular genetic tests
-clinical diagnosis/confirmation
-carrier screening
-prenatal diagnosis
-newborn screen
-presymptomatic diagnosis/predisposition screening
molecular genetics vs molecular oncology
molecular genetics more concerned w/ inherited mutations

molecular oncology concerned w/ somatic mutations
application of DNA testing
-transplantation entrapment
-paternity testing
-forensic ID
-twin zygosity -mono vs. zygotic twins
-surgical mix-ups
-vet applications
methods of analysis & interpretation
-frequency of given matching allels multiply together = cumulative probablility

match = inclusion
mismatch = exclusion
how do you detect & compare polymorphisms?
Souther Blot-longer
VNTR=Variable Number Tandem
RFLP= Restriction Fragment Length Polymorphisms

STR=Short Tandem Repeats
SNP=Single Nucleotide Polymorphisms
Types of DNA polymorphisms found in DNA fingerprinting
 RFLP = Restriction Fragment Length Polymorphisms - restriction endonuclease recognition sites that are present in some people but not in others

 VNTR = Variable Number Tandem Repeats - strings of nucleotide sequences (usually of 16 or more nucleotides each), of different repeat number in different people, existing between fixed restriction endonuclease sites; also called minisatellites

 STR = Short Tandem Repeats - strings of oligonucleotide sequences that are shorter than VNTR (usually of 2, 3, 4, or 8 nucleotides each), of different repeat number in different people, not necessarily lying between restriction endonuclease sites; also called microsatellites

 SNP = Single Nucleotide Polymorphisms - single nucleotide differences between individuals that are not associated with restriction endonuclease sites

 HLA = the histocompatibility family of genes located on chromosome 6p; although not "junk" DNA, these genes are naturally so highly polymorphic that they can be used for identity studies at either the DNA level or using antibodies to distinguish varieties in the encoded proteins
mitochonrial mutation
-maternal inheritance
-heteroplasmy may require biopsy of affected tissue
diseases of trinucleotide Repeat Expansions
-fragile X
-fredreich ataxia
-myotonic dystrophy
-spinocerebellar ataxia
diseases where gene is known but not mutation
-duchenne muscular dystrophy (2/3 due to large deletions
-cystic fibrosis (>1300 mutations)
-familial breast cancer
-multiple endocrine neoplasm
diseases for which both disease & mutation are known
-sickle cell anemia
-factor V leiden
By order of diagnostic difficulty, the molecular classes of genetic diseases are
1)both gene & causitive mutation known
2)gene known; mutation not
3)neither gene nor mutation known
4) caused by more than 1 gene interacting w/ enviornmental factors (polygenic & multifactorial)
Unique features of molecular diagnostics of genetic diseases
-examining individuals unique genotype
-test results have implications for blood reletives
-specimens from family members may be required (e.g., linkage testing)
-can predict disease before onset
-can predict disease before birth
To detect many possible mutations in diseases w/ marked genetic heterogenity use:
-PCR -several gene regions followed by sevel hybridization w/ panel of ASO probes

-Dot Blot -hybridization w/ pooled cocktail of ASO probes for several rare mutations at once

-PCR followed by reverse dot blot hybridization to an array of ASO probes bound to a paper strip or other solid support (e.g, cystic fibrosis)

-Manual or automated DNA sequencing (e.g., BRCA 1/2)

-Mutation scanning techniques (DGGE, SSCP, PTT)

-DNA chip
To detect trinucleotide repeat expansions use:
-sizing by PCR if expansion is of moderate length
-sizing by southern blot if expansion is of lare size ( too large for PCR)
For large deletions use:
-southern Blot
-fluorescence in sito hybridization (FISH)
-routine cytogenetics, if deletion is big enough to be visualized by light microscopy
-multiplex PCR (deletions of duchenne muscular distrophy)
For pt mutations & microdeletions/microinsertions use:
-southern blot or dot blot hybridization w/ ASO probes
-southern blot or PCR amplification, subjcting the products to digestion w/ particular restriction endonuclease whose natural cleavage sequence is either destroyed or created by mutation in question
- DNA sequence
Utility of PCR
-extremely sensitive
-large # of specimens
-not good for large regions of DNA
genetic heterogenety
many genetic & neoplastic diseases can be caused by more than 1 mutation, or more than one gene
Types of mutations & results:
-pt mutation- missense or nonsense coding, errors in RNA splicing
Types of mutations & resutls:
1)pt mutation - missense or nonsence coding, errors in RNA splicing
2) microdeletion - frameshift mutation
3)deletions- minus large portion of gene
4) trinucleotide repeat expansion
5) translocations - xchange b/n 2 chromosomes
6)rearrangement - shifting on same chromosome
7) amplifications - increase copy number of gene
trinucleotide repeat expansion
-tandem triplet repeat enlarges to greater than normal leanght w/in gene
-common in neuromuscular diseases
Southern Blot
a techniqe for probing gene sx involving endonuclease digestion of target DNA followed by gel electrophoresis, transfer of DNA fragment to a filter membrane, & hybridization w/ a DNA probe
Predictive genetic testing
analysis of mutation causing late onset, usually dominant diseases in presently healthy people
benign sequence change w/in DNA that is reletively common in the population
point mutation
a localized defect w/in a gene consisting of substitution of a single nucleotide or sometimes a small deletion or insertion
polymerase chain rxn - powerful technique for amplifying a specific region of a gene to obtain abundant purified DNA for further analysis
mutation scanning
any number of tecniques designed to detect presence of an unknown nucleotide change in gene, based on the resulting change in the genes physicochemical properties
linkage analysis
technique for tracking mutant gene w/n a family by deletion of polymorphisms located closely on same chromosome; required when direct mutation detection is not possilble because disease gene is unknown
dot blot
hybridization of DNA probe to a target specimen. Spotted onto a filter membrane
DNA sequencing
technique, manual or automated, delineating the order of nucleotides in gene or gene fragment
DNA fingerprinting
use of complex dna polymorphic patterns to ID & match individuals or specimens
direct mutation testing
detection of specific mutations in known disease genes
sizable defect in gene due to loss of a stretch of nucleotides
allele specific oligonucleotide- a short DNA probe that will specifically hybridize to either the normal gene or any particular gene sequence.