MOLECULAR DIAGNOSTICS - WEEK
#1 INTRODUCTION TO MOLECULAR
DIAGNOSTICS EXAM QUESTIONS
WITH COMPLETE ANSWERS
Sperm - ANSWER-Excellent source of DNA, 5 ul gives as much as 50 ul of blood.
Useful in sexual assault cases. Must perform *differential* extraction
1. Vaginal epithelium of victim
2. DNA from perpetrator's semen
Saliva - ANSWER-May contain oral epithelial cells and be present on a variety of
materials/objects:
bite marks
cigarette butts
postage stamps
envelope flaps
Hair - ANSWER-Must include the follicle and may contain epithelial cells from the
scalp.
Bone - ANSWER-May be used to identify decomposed remains
Teeth - ANSWER-Excellent source of DNA which, like bone, remains viable long
after the body's decay
Advantages of Molecular Testing - ANSWER-1. Enhanced analytical specificity and
sensitivity (molecular methods *directly* identify pathogenic DNA sequences)
2. Detection of *single* cells
3. Monitoring of microorganisms (can detect as few as *50* copies of DNA/RNA, viral
loads)
4. Genotyping to detect minor variations in base sequences (can assist with
identifying antibiotic resistance, effectiveness of chemotherapies)
Disadvantages of Molecular Testing - ANSWER-1. Higher cost-per-test
2. Low reimbursement
3. Potential for contamination resulting in false positives
4. Highly-complex testing requires investment in appropriately trained, educated
personnel
Technical Considerations for Molecular Testing - ANSWER-1. A genetic *target* is
required for a specific disorder
2. Requires an appropriate *source* of nucleic acids
3. Nature of mutation must be known
4. Sensitivity of the detection method should be understood
, Clinical Applications of Molecular Diagnostics - Inherited Diseases - ANSWER-May
be used in their diagnosis, treatment and management. Examples include Fragile X
syndrome, Leiden Factor V and hereditary hemochromatosis
Clinical Applications of Molecular Diagnostics - Infectious Diseases - ANSWER-
Molecular techniques may be used to monitor treatment, determine viral loads, drug
sensitivity and to perform genotyping. Can apply to viruses (e.g. Epstein-Barr Virus,
Cytomegalovirus, Human Immunodeficiency Virus) and bacteria (e.g. Mycobacterium
tuberculosis, Neisseria gonorrhoeae, Chlamydia trachomatis) as well as fungi,
protozoa etc.
Molecular Diagnostics - ANSWER-Combination of laboratory medicine, molecular
genetics and technology
Molecular Diagnostics in Health Care - ANSWER-Techniques allow detection of
pathogenic mutations in nucleic acids to facilitate detection, diagnosis, classification,
prognosis and therapy monitoring
Clinical Applications of Molecular Diagnostics - Cancer - ANSWER-Used in
diagnosis, classification, stage determination and tumor analyses. Example
conditions include B/T cell lymphomas, CML, Ewings sarcoma and
Rhabdomyosarcoma
Peripheral Blood - ANSWER-White Blood Cells are required as red blood cells do
not contain nuclei. Typically 50 ul is sufficient for most molecular testing
Molecular-based Analyses - Chromosomal Disorders - ANSWER-Detects the loss,
gain or abnormal arrangement of genetic material. May result in birth defects,
hematopoietic malignancies. Are classified as *monogenic* i.e. resulting from
mutation in a single gene or *polygenic* i.e. resulting from interplay of multiple
genetic factors.
Monogenic Disorder - ANSWER-Chromosomal disorder resulting from a mutation in
a single gene. Conforms to traditional Mendelian inheritance, with a frequency of
10/1000 live births
Polygenic Disorder - ANSWER-Chromosomal disorder resulting from the interaction
of mutations in multiple genes. Unlike monogenic disorders, they do not conform to
Mendelian inheritance patterns. Examples: hypertension, Alzheimer's disease,
Diabetes mellitus, Cancer, congenital malformations
Mutation - ANSWER-*Permanent* alteration of a DNA sequence, usually found in
less than 1% or 2% of a given population
Polymorphism - ANSWER-Difference in DNA sequence found in 1% to 2% or *more*
of a given population
Mutation Structure - ANSWER-Analyzed by *endonuclease digestion* which can
determine variation in fragment lengths.
#1 INTRODUCTION TO MOLECULAR
DIAGNOSTICS EXAM QUESTIONS
WITH COMPLETE ANSWERS
Sperm - ANSWER-Excellent source of DNA, 5 ul gives as much as 50 ul of blood.
Useful in sexual assault cases. Must perform *differential* extraction
1. Vaginal epithelium of victim
2. DNA from perpetrator's semen
Saliva - ANSWER-May contain oral epithelial cells and be present on a variety of
materials/objects:
bite marks
cigarette butts
postage stamps
envelope flaps
Hair - ANSWER-Must include the follicle and may contain epithelial cells from the
scalp.
Bone - ANSWER-May be used to identify decomposed remains
Teeth - ANSWER-Excellent source of DNA which, like bone, remains viable long
after the body's decay
Advantages of Molecular Testing - ANSWER-1. Enhanced analytical specificity and
sensitivity (molecular methods *directly* identify pathogenic DNA sequences)
2. Detection of *single* cells
3. Monitoring of microorganisms (can detect as few as *50* copies of DNA/RNA, viral
loads)
4. Genotyping to detect minor variations in base sequences (can assist with
identifying antibiotic resistance, effectiveness of chemotherapies)
Disadvantages of Molecular Testing - ANSWER-1. Higher cost-per-test
2. Low reimbursement
3. Potential for contamination resulting in false positives
4. Highly-complex testing requires investment in appropriately trained, educated
personnel
Technical Considerations for Molecular Testing - ANSWER-1. A genetic *target* is
required for a specific disorder
2. Requires an appropriate *source* of nucleic acids
3. Nature of mutation must be known
4. Sensitivity of the detection method should be understood
, Clinical Applications of Molecular Diagnostics - Inherited Diseases - ANSWER-May
be used in their diagnosis, treatment and management. Examples include Fragile X
syndrome, Leiden Factor V and hereditary hemochromatosis
Clinical Applications of Molecular Diagnostics - Infectious Diseases - ANSWER-
Molecular techniques may be used to monitor treatment, determine viral loads, drug
sensitivity and to perform genotyping. Can apply to viruses (e.g. Epstein-Barr Virus,
Cytomegalovirus, Human Immunodeficiency Virus) and bacteria (e.g. Mycobacterium
tuberculosis, Neisseria gonorrhoeae, Chlamydia trachomatis) as well as fungi,
protozoa etc.
Molecular Diagnostics - ANSWER-Combination of laboratory medicine, molecular
genetics and technology
Molecular Diagnostics in Health Care - ANSWER-Techniques allow detection of
pathogenic mutations in nucleic acids to facilitate detection, diagnosis, classification,
prognosis and therapy monitoring
Clinical Applications of Molecular Diagnostics - Cancer - ANSWER-Used in
diagnosis, classification, stage determination and tumor analyses. Example
conditions include B/T cell lymphomas, CML, Ewings sarcoma and
Rhabdomyosarcoma
Peripheral Blood - ANSWER-White Blood Cells are required as red blood cells do
not contain nuclei. Typically 50 ul is sufficient for most molecular testing
Molecular-based Analyses - Chromosomal Disorders - ANSWER-Detects the loss,
gain or abnormal arrangement of genetic material. May result in birth defects,
hematopoietic malignancies. Are classified as *monogenic* i.e. resulting from
mutation in a single gene or *polygenic* i.e. resulting from interplay of multiple
genetic factors.
Monogenic Disorder - ANSWER-Chromosomal disorder resulting from a mutation in
a single gene. Conforms to traditional Mendelian inheritance, with a frequency of
10/1000 live births
Polygenic Disorder - ANSWER-Chromosomal disorder resulting from the interaction
of mutations in multiple genes. Unlike monogenic disorders, they do not conform to
Mendelian inheritance patterns. Examples: hypertension, Alzheimer's disease,
Diabetes mellitus, Cancer, congenital malformations
Mutation - ANSWER-*Permanent* alteration of a DNA sequence, usually found in
less than 1% or 2% of a given population
Polymorphism - ANSWER-Difference in DNA sequence found in 1% to 2% or *more*
of a given population
Mutation Structure - ANSWER-Analyzed by *endonuclease digestion* which can
determine variation in fragment lengths.
