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Why might females occasionally be affected by X-linked recessive diseases? A) Due to skewed X-inactivation B) Because they have two Y chromosomes C) Because they inherit two mutant alleles D) Due to environmental factors E) Because they have an extra X chromosome
A) Due to skewed X-inactivation Explanation: Females might be affected by X-linked recessive diseases if skewed X-inactivation occurs, leading to the inactivation of the normal allele and expression of the mutant allele.
What is the primary use of karyotyping in modern genetic testing? A) Detecting microdeletions B) Identifying balanced chromosomal rearrangements C) Diagnosing single-gene disorders D) Detecting point mutations E) Screening for common genetic variants
B) Identifying balanced chromosomal rearrangements Explanation: Karyotyping is now predominantly offered in cases of unexplained infertility to identify balanced chromosomal rearrangements, which may affect fertility by disrupting the formation of germ cells.
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p.2
X-Linked Recessive Diseases

Why might females occasionally be affected by X-linked recessive diseases?
A) Due to skewed X-inactivation
B) Because they have two Y chromosomes
C) Because they inherit two mutant alleles
D) Due to environmental factors
E) Because they have an extra X chromosome

A) Due to skewed X-inactivation
Explanation: Females might be affected by X-linked recessive diseases if skewed X-inactivation occurs, leading to the inactivation of the normal allele and expression of the mutant allele.

p.4
Genetic Testing Techniques

What is the primary use of karyotyping in modern genetic testing?
A) Detecting microdeletions
B) Identifying balanced chromosomal rearrangements
C) Diagnosing single-gene disorders
D) Detecting point mutations
E) Screening for common genetic variants

B) Identifying balanced chromosomal rearrangements
Explanation: Karyotyping is now predominantly offered in cases of unexplained infertility to identify balanced chromosomal rearrangements, which may affect fertility by disrupting the formation of germ cells.

p.6
Genetic Testing Techniques

What is available separately for cancer genetics?
A) A general genetic test directory
B) A national genetic test directory for cancer
C) A list of clinical geneticists
D) A directory of primary care physicians
E) A guide for laboratory technicians

B) A national genetic test directory for cancer
Explanation: A separate national genetic test directory for cancer is available, providing specific resources and information for cancer-related genetic testing.

p.5
Genetic Testing Techniques

What is the primary advantage of high-throughput sequencing technology in human genetics?
A) It is cheaper than traditional methods
B) It involves fragmenting and sequencing short stretches of patient DNA
C) It can detect all types of genetic errors
D) It requires no computer software
E) It is only used for prenatal testing

B) It involves fragmenting and sequencing short stretches of patient DNA
Explanation: High-throughput sequencing technology involves fragmenting and sequencing short stretches of patient DNA and comparing them to a reference sequence using computer software, which has revolutionized the field of human genetics.

p.2
X-Linked Recessive Diseases

Which of the following is an example of an X-linked recessive condition?
A) Cystic Fibrosis
B) Hemophilia A
C) Down Syndrome
D) Huntington's Disease
E) Marfan Syndrome

B) Hemophilia A
Explanation: Hemophilia A is an X-linked recessive condition caused by a deficiency in factor VIII.

p.5
Genetic Testing Techniques

What is the purpose of the National Genomic Medicine Service (GMS) launched in 2019?
A) To replace all traditional medical practices
B) To integrate genetic medicine into routine healthcare
C) To eliminate the need for prenatal testing
D) To provide free healthcare to all citizens
E) To focus solely on cancer treatment

B) To integrate genetic medicine into routine healthcare
Explanation: The National Genomic Medicine Service (GMS) aims to integrate genetic medicine into routine healthcare, ensuring consistent and equitable care for everyone.

p.3
Prader-Willi Syndrome

In Prader-Willi Syndrome (PWS), the mutated chromosome is always derived from which parent?
A) Maternal
B) Paternal
C) Either parent
D) Grandparent
E) Sibling

B) Paternal
Explanation: In Prader-Willi Syndrome (PWS), the mutated chromosome is always paternally derived, which is a key aspect of its genetic inheritance.

p.3
Complex Inheritance Disorders

What is the inheritance pattern of hereditary glomus tumor?
A) Autosomal dominant
B) Autosomal recessive
C) X-linked recessive
D) Mitochondrial inheritance
E) Y-linked inheritance

A) Autosomal dominant
Explanation: Hereditary glomus tumor is an example of a single gene disease with autosomal dominant inheritance, typically seen in individuals who inherit the mutant allele from their father.

p.1
Sickle Cell Disease

Which population is most commonly affected by Sickle Cell Disease?
A) Caucasian
B) African and Caribbean
C) Asian
D) Native American
E) Pacific Islander

B) African and Caribbean
Explanation: Sickle Cell Disease is particularly prevalent in individuals with African or Caribbean heritage, where the mutant allele is maintained at high frequency due to its protective effect against malaria in the heterozygous state.

p.4
Genetic Testing Techniques

What is the range of deletions or duplications seen in microdeletions/duplication syndromes?
A) Less than 1 kb
B) Less than 5 kb
C) Less than 10 kb
D) Less than 50 kb
E) Less than 100 kb

B) Less than 5 kb
Explanation: Deletions or duplications in the range of less than 5 kb (5 million base pairs) are seen in microdeletions/duplication syndromes.

p.4
Cystic Fibrosis

Which genetic disorder is commonly diagnosed using DNA sequencing due to its well-characterized phenotype?
A) Cystic Fibrosis
B) DiGeorge syndrome
C) Klinefelter syndrome
D) Prader-Willi syndrome
E) Angelman syndrome

A) Cystic Fibrosis
Explanation: Cystic Fibrosis is commonly diagnosed using DNA sequencing because it has a well-characterized phenotype and a limited number of common variants that cause the majority of cases.

p.1
Cystic Fibrosis

What is the carrier frequency of Cystic Fibrosis in the U.S. Caucasian population?
A) 1 in 10
B) 1 in 25
C) 1 in 50
D) 1 in 100
E) 1 in 200

B) 1 in 25
Explanation: Cystic Fibrosis is the most common autosomal recessive disorder in the U.S. Caucasian population, with a carrier frequency of about 1 in 25 individuals.

p.1
Thalassemias

What is the primary characteristic of Thalassemias?
A) Abnormal hemoglobin production
B) Excessive iron absorption
C) Increased white blood cell count
D) High blood pressure
E) Increased bone density

A) Abnormal hemoglobin production
Explanation: Thalassemias are a group of inherited blood disorders characterized by abnormal hemoglobin production, leading to various forms of anemia.

p.6
Genetic Testing Techniques

What is the main benefit of implementing the genetic testing service for clinicians?
A) Reduced need for clinical geneticists
B) Increased patient referrals
C) Higher costs for patients
D) Limited access to genetic tests
E) More complex testing procedures

A) Reduced need for clinical geneticists
Explanation: The implementation of this service allows clinicians to order genetic testing without having to refer their patients to a clinical geneticist, streamlining the process and making it more accessible.

p.6
Genetic Testing Techniques

What is the purpose of targeted genetic testing for patients?
A) To increase the cost of healthcare
B) To delay the diagnosis process
C) To guide management for the patient and/or their family
D) To replace all other forms of testing
E) To reduce the accuracy of diagnosis

C) To guide management for the patient and/or their family
Explanation: Targeted genetic testing is aimed at patients where a genetic or genomic diagnosis will guide management for them and/or their family, providing crucial information for treatment and care.

p.4
Genetic Testing Techniques

Which syndrome is associated with a 22q11.2 deletion?
A) Williams-Beuren syndrome
B) DiGeorge syndrome
C) Prader-Willi syndrome
D) Angelman syndrome
E) Klinefelter syndrome

B) DiGeorge syndrome
Explanation: DiGeorge syndrome is associated with a 22q11.2 deletion.

p.4
Genetic Testing Techniques

What is the main limitation of microarray technology in genetic testing?
A) Cannot detect balanced translocations
B) Requires dividing cells
C) Low sensitivity
D) Slow procedure
E) High cost

A) Cannot detect balanced translocations
Explanation: Microarray technology cannot be used to detect balanced translocations, which is a limitation compared to other genetic testing methods.

p.3
Prader-Willi Syndrome

What is Prader-Willi Syndrome (PWS) characterized by?
A) Developmental delay, obesity, and hyperphagia
B) Ataxic movements, seizures, and frequent laughter
C) Hyperactivity and attention deficit
D) Muscle weakness and respiratory issues
E) Skin rashes and joint pain

A) Developmental delay, obesity, and hyperphagia
Explanation: Prader-Willi Syndrome (PWS) is characterized by developmental delay, obesity, and hyperphagia, which are key symptoms of this genetic disorder.

p.3
Genetic Imprinting

What is Uniparental Disomy (UPD)?
A) Inheriting one copy of a chromosome from each parent
B) Inheriting both copies of a chromosome from one parent
C) Inheriting extra copies of a chromosome
D) Inheriting a chromosome deletion
E) Inheriting a chromosome translocation

B) Inheriting both copies of a chromosome from one parent
Explanation: Uniparental Disomy (UPD) occurs when a child inherits both copies of a chromosome from one parent, which can lead to genetic disorders if the chromosome carries imprinted genes.

p.2
X-Linked Recessive Diseases

Why are females who inherit a mutant allele carried on the X chromosome usually unaffected?
A) They have two Y chromosomes
B) They have a protective gene on the Y chromosome
C) They have a normal allele on their other X chromosome
D) They have a higher tolerance for mutations
E) They have an extra X chromosome

C) They have a normal allele on their other X chromosome
Explanation: Females usually have two X chromosomes, so if one carries a mutant allele, the normal allele on the other X chromosome can often compensate, protecting them from the effects of the mutation.

p.2
X-Linked Recessive Diseases

What is the risk that the sons of a carrier female will be affected by an X-linked recessive disease?
A) 0%
B) 25%
C) 50%
D) 75%
E) 100%

C) 50%
Explanation: There is a 50% risk that the sons of a carrier female will inherit the mutant X chromosome and be affected by the disease.

p.5
Genetic Screening in Obstetrics

What is the detection rate of non-invasive prenatal testing (NIPT) for Down syndrome?
A) 50%
B) 75%
C) 85%
D) 99%
E) 100%

D) 99%
Explanation: Non-invasive prenatal testing (NIPT) is a very sensitive screening test with a detection rate for Down syndrome of around 99%.

p.3
Prader-Willi Syndrome

What is Angelman Syndrome (AS) characterized by?
A) Developmental delay, ataxic movements, seizures, and frequent laughter
B) Obesity and hyperphagia
C) Muscle weakness and respiratory issues
D) Skin rashes and joint pain
E) Hyperactivity and attention deficit

A) Developmental delay, ataxic movements, seizures, and frequent laughter
Explanation: Angelman Syndrome (AS) is characterized by developmental delay, ataxic movements, seizures, and frequent laughter, which are distinctive features of this genetic disorder.

p.3
Genetic Imprinting

Which syndrome is associated with paternal UPD of chromosome 11?
A) Beckwith-Wiedemann Syndrome
B) Russell-Silver Syndrome
C) Prader-Willi Syndrome
D) Angelman Syndrome
E) Down Syndrome

A) Beckwith-Wiedemann Syndrome
Explanation: Beckwith-Wiedemann Syndrome is associated with paternal UPD of chromosome 11, which affects the expression of imprinted genes in this region.

p.1
Cystic Fibrosis

What is the typical life expectancy for individuals born with Cystic Fibrosis today?
A) 10-20 years
B) 20-30 years
C) 30-40 years
D) 40-50 years
E) 50-60 years

C) 30-40 years
Explanation: Due to improvements in management and the availability of lung transplants, many children born with Cystic Fibrosis today will live into their mid-30s or 40s.

p.6
Genetic Testing Techniques

In what instances will the G3H review the test request and relevant clinical information?
A) When the patient requests it
B) When the clinical indication is unclear
C) When the test is inexpensive
D) When the test is already approved
E) When the test is for a common condition

B) When the clinical indication is unclear
Explanation: The G3H will review the test request and relevant clinical information in instances where the testing is requested by the clinical indication, ensuring that the most appropriate constituent test(s) are selected.

p.5
Genetic Testing Techniques

What is a limitation of high-throughput sequencing technologies?
A) It can detect all genetic variations
B) It is always conclusive
C) It cannot detect imprinting errors
D) It is inexpensive
E) It does not require any expertise

C) It cannot detect imprinting errors
Explanation: High-throughput sequencing technologies cannot be used to detect imprinting errors, UPD, nucleotide repeats, or expansions.

p.3
Prader-Willi Syndrome

Which chromosome region is involved in both Prader-Willi Syndrome (PWS) and Angelman Syndrome (AS)?
A) 15q11–13
B) 21q22
C) 7q31
D) 11p15
E) 5p15

A) 15q11–13
Explanation: Both Prader-Willi Syndrome (PWS) and Angelman Syndrome (AS) involve genetic variations in the same region of chromosome 15q11–13.

p.3
Complex Inheritance Disorders

Which of the following is an example of a complex inheritance disorder?
A) Cystic Fibrosis
B) Sickle Cell Disease
C) Congenital heart disease
D) Hemophilia
E) Duchenne Muscular Dystrophy

C) Congenital heart disease
Explanation: Congenital heart disease is an example of a complex inheritance disorder, which involves multiple genes interacting with environmental and lifestyle factors.

p.1
Autosomal Recessive Disorders

Which of the following is NOT an example of an autosomal recessive condition?
A) Cystic Fibrosis
B) Congenital adrenal hyperplasia
C) Usher syndrome
D) Hemophilia
E) Galactosemia

D) Hemophilia
Explanation: Hemophilia is an X-linked recessive disorder, not an autosomal recessive condition. The other conditions listed are examples of autosomal recessive disorders.

p.1
Sickle Cell Disease

What is the genetic cause of Sickle Cell Disease?
A) A single amino acid change in the hemoglobin molecule
B) A deletion in the CFTR gene
C) A duplication of the alpha-globin gene
D) A mutation in the insulin gene
E) A deficiency in the enzyme G6PD

A) A single amino acid change in the hemoglobin molecule
Explanation: Sickle Cell Disease is caused by a single amino acid change from valine to glutamine in the hemoglobin molecule, resulting from a single base-pair substitution in the HBB gene.

p.6
Genetic Testing Techniques

Who will triage referrals to ensure the most appropriate test is performed?
A) The patient's family
B) The local G3H
C) The clinical geneticist
D) The patient's primary care physician
E) The laboratory technician

B) The local G3H
Explanation: The local G3H will triage referrals to ensure that the most appropriate test is performed, ensuring that the testing process is efficient and accurate.

p.5
Genetic Screening in Obstetrics

What percentage of cell-free fetal DNA (cffDNA) accounts for in maternal blood?
A) 1% to 5%
B) 10% to 20%
C) 30% to 40%
D) 50% to 60%
E) 70% to 80%

B) 10% to 20%
Explanation: Cell-free fetal DNA (cffDNA) accounts for between 10% and 20% of the total cell-free DNA in maternal blood.

p.3
Genetic Testing Techniques

Which genetic testing technique is used to detect chromosomal abnormalities and is often performed in combination with other methods?
A) Karyotyping
B) PCR
C) Western Blot
D) ELISA
E) Southern Blot

A) Karyotyping
Explanation: Karyotyping is a cytogenetic technique used to analyze the chromosomal content of a cell and detect numerical and structural abnormalities. It is often performed in combination with other methods for comprehensive genetic analysis.

p.2
X-Linked Recessive Diseases

What is the main characteristic of an X-linked recessive family pedigree?
A) Only females are affected
B) Both males and females are equally affected
C) Usually only males are affected
D) The disease skips generations
E) The disease is always lethal

C) Usually only males are affected
Explanation: In X-linked recessive diseases, males are usually affected because they have only one X chromosome, so a single mutant allele will cause the disease.

p.5
Genetic Screening in Obstetrics

What is the diagnostic hit rate of traditional karyotyping or microarray analysis in pregnancies with ultrasound anomalies?
A) 50% to 60%
B) 25% to 30%
C) 14% to 16%
D) 2% to 3%
E) 99%

C) 14% to 16%
Explanation: Traditional karyotyping or microarray analysis has a diagnostic hit rate of around 14% to 16% in pregnancies with ultrasound anomalies.

p.4
Genetic Testing Techniques

Which technique allows for the simultaneous analysis of multiple regions of DNA in a single reaction?
A) Karyotyping
B) FISH
C) MLPA (Multiplex Ligation-dependent Probe Amplification)
D) Sanger sequencing
E) Southern blotting

C) MLPA (Multiplex Ligation-dependent Probe Amplification)
Explanation: MLPA is a PCR-based method that allows for the simultaneous analysis of multiple regions of DNA in a single reaction, making it useful for detecting small deletions and duplications.

p.3
Genetic Testing Techniques

What is the main limitation of karyotyping?
A) It is time-consuming and costly
B) It cannot detect numerical abnormalities
C) It is only used for protein analysis
D) It cannot be used for prenatal diagnosis
E) It is not useful for detecting large imbalances

A) It is time-consuming and costly
Explanation: Karyotyping, while considered the gold standard for many years, is time-consuming and costly, which are significant limitations of this genetic testing technique.

p.1
Sickle Cell Disease

What is the primary characteristic of Sickle Cell Disease?
A) Deficiency in white blood cells
B) Deformation of red blood cells into a sickle shape
C) Excessive production of red blood cells
D) Increased blood clotting
E) High levels of cholesterol

B) Deformation of red blood cells into a sickle shape
Explanation: Sickle Cell Disease is characterized by the tendency of red blood cells to deform into a sickle shape under low oxygen conditions, leading to various complications.

p.4
Genetic Testing Techniques

What is an advantage of Fluorescence in situ Hybridization (FISH) over traditional karyotyping?
A) Requires dividing cells
B) Less sensitive
C) Can detect microdeletions and duplications
D) Slower procedure
E) Lower resolution

C) Can detect microdeletions and duplications
Explanation: An advantage of FISH is that, unlike traditional karyotyping, it does not require dividing cells and is more sensitive, allowing for the detection of microdeletions and duplications.

p.4
Genetic Testing Techniques

What is the first-line test for the diagnosis of aneuploidies such as trisomy 13 and 18?
A) Karyotyping
B) FISH
C) QF-PCR (Quantitative Fluorescence Polymerase Chain Reaction)
D) MLPA
E) Southern blotting

C) QF-PCR (Quantitative Fluorescence Polymerase Chain Reaction)
Explanation: QF-PCR is a rapid, robust, and cost-effective test for the detection of copy number variation and is now the first-line test for the diagnosis of aneuploidies such as trisomy 13 and 18.

p.1
Autosomal Recessive Disorders

What is the probability of a child being affected by an autosomal recessive disorder if both parents are carriers?
A) 1 in 2
B) 1 in 3
C) 1 in 4
D) 1 in 5
E) 1 in 6

C) 1 in 4
Explanation: For an individual to be affected with an autosomal recessive disorder, both parents must be carriers. In this case, there is a 1 in 4 chance of having an affected child each time they have a child.

p.1
Cystic Fibrosis

What is the primary cause of Cystic Fibrosis?
A) Variations in the gene encoding a chloride channel protein
B) Deficiency in insulin production
C) Mutation in the hemoglobin gene
D) Lack of vitamin D
E) Excessive iron absorption

A) Variations in the gene encoding a chloride channel protein
Explanation: Cystic Fibrosis is caused by variations in the gene encoding the cystic fibrosis transmembrane conductance regulator (CFTR), a chloride channel protein.

p.1
Cystic Fibrosis

Which of the following is a common symptom of Cystic Fibrosis?
A) High blood pressure
B) Thick, sticky secretions
C) Excessive hair growth
D) Increased bone density
E) Frequent nosebleeds

B) Thick, sticky secretions
Explanation: Variations in the CFTR gene lead to the production of thick, sticky secretions, resulting in lung disease and recurrent bacterial infections, among other symptoms.

Study Smarter, Not Harder
Study Smarter, Not Harder