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What is the primary mechanism of Allele-Specific PCR for detecting gene variations?
It uses specialized primers designed for a perfect match with a specific gene version; a perfect fit allows DNA replication and amplification, while a mismatch prevents it.
Просматривай карточки здесь или sign up to study with spaced repetition.
Why is 'multiplexing' advantageous in Allele-Specific PCR?
It allows multiple different mutations to be tested simultaneously in a single reaction, making the process highly efficient for routine screenings.
Просматривай карточки здесь или sign up to study with spaced repetition.
What is a major limitation of standard PCR in detecting heterozygous deletions?
It only detects duplications but not deletions.
The reaction is too slow to provide clinical results.
The normal allele amplifies even when the other allele is deleted, masking the deletion.
It requires too much DNA sample to be viable.
What is a major limitation of standard PCR in detecting heterozygous deletions?
It only detects duplications but not deletions.
The reaction is too slow to provide clinical results.
The normal allele amplifies even when the other allele is deleted, masking the deletion.
It requires too much DNA sample to be viable.
Просматривай карточки здесь или sign up to study with spaced repetition.
What is the current gold standard technique for detecting Copy Number Variants (CNVs)?
MLPA (Multiplex Ligation-dependent Probe Amplification).
Просматривай карточки здесь или sign up to study with spaced repetition.
How does MLPA identify specific exon deletions in a patient sample?
By comparing a patient's DNA profile against a standard control profile, identifying specific missing or reduced peaks in the test data.
Просматривай карточки здесь или sign up to study with spaced repetition.
Which form of Spinal Muscular Atrophy (SMA) is considered the most severe?
SMA1
SMA4
SMA0
SMA2
Which form of Spinal Muscular Atrophy (SMA) is considered the most severe?
SMA1
SMA4
SMA0
SMA2
Просматривай карточки здесь или sign up to study with spaced repetition.
In SMA patients, what is the primary determinant of the phenotype's severity?
The number of SMN2 gene copies.
Просматривай карточки здесь или sign up to study with spaced repetition.
What is the consequence of the silent mutation present in the SMN2 gene?
It creates an exonic splicing site that causes transcripts to miss exon 7, resulting in only 5% of transcripts producing complete protein.
Просматривай карточки здесь или sign up to study with spaced repetition.
What specific challenge is encountered when counting SMN2 gene copies?
The physical arrangement of the copies is unknown; it is impossible to determine if copies are on one allele or both, preventing accurate genotype prediction in offspring.
Просматривай карточки здесь или sign up to study with spaced repetition.
What genetic condition is cited as a reason for using a highly targeted testing approach?
BRCA1-related breast cancer
SMA
Neurofibromatosis type 1
Achondroplasia
What genetic condition is cited as a reason for using a highly targeted testing approach?
BRCA1-related breast cancer
SMA
Neurofibromatosis type 1
Achondroplasia
Просматривай карточки здесь или sign up to study with spaced repetition.
What is the recurrence risk for a child with SMA when both parents carry one SMN1 copy?
25%
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What is the estimated recurrence risk for a child with SMA in the case of de novo mutations?
Low
Просматривай карточки здесь или sign up to study with spaced repetition.
Name two mechanisms of SMN gene rearrangement.
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Why is the frequency of de novo rearrangements in SMA considered high for a recessive disease?
Genetic drift in modern populations.
High rates of environmental mutagen exposure.
The structure of chromosome 5q increases the risk of rearrangements that cause deletions in SMN1.
Polygenic inheritance patterns.
Why is the frequency of de novo rearrangements in SMA considered high for a recessive disease?
Genetic drift in modern populations.
High rates of environmental mutagen exposure.
The structure of chromosome 5q increases the risk of rearrangements that cause deletions in SMN1.
Polygenic inheritance patterns.
Просматривай карточки здесь или sign up to study with spaced repetition.
What does a '2+0' arrangement signify regarding SMN1 gene copies?
One chromosome has 2 copies of the gene and the other chromosome has 0 copies.
Просматривай карточки здесь или sign up to study with spaced repetition.
Why is the '2+0' SMN1 arrangement difficult to detect with standard screening?
Because the copies are located on different chromosomes entirely.
Because the standard test cannot distinguish between the presence of one gene on each chromosome versus two genes on a single chromosome.
Because the copies are silenced by methylation.
Because it occurs exclusively in males.
Why is the '2+0' SMN1 arrangement difficult to detect with standard screening?
Because the copies are located on different chromosomes entirely.
Because the standard test cannot distinguish between the presence of one gene on each chromosome versus two genes on a single chromosome.
Because the copies are silenced by methylation.
Because it occurs exclusively in males.
Просматривай карточки здесь или sign up to study with spaced repetition.
What is the primary limitation of population screening for SMN1 deletions regarding SMA subtypes?
It cannot predict the SMA subtype because the SMN2 copy number is unknown.
Просматривай карточки здесь или sign up to study with spaced repetition.
How are newborns screened for SMA in neonatal programs?
Through PCR amplifying the SMA region.
Просматривай карточки здесь или sign up to study with spaced repetition.
What is the difference between SMN1 and SMN2 regarding exon 7?
A nucleotide change in SMN2 abolishes an Exonic Splicing Enhancer (ESE) and favors an Intronic Splicing Silencer (ISS), leading to the skipping of exon 7.
Просматривай карточки здесь или sign up to study with spaced repetition.
What is the function of the drug Spinraza in treating SMA?
It is an antisense oligonucleotide that binds to an intronic splicing silencer, preventing the skipping of exon 7 and restoring functional protein production.
Просматривай карточки здесь или sign up to study with spaced repetition.
Why is administration of antisense oligonucleotide drugs for SMA complex?
Because the body rapidly metabolizes the drug before it reaches the CNS.
Because the drug must be administered intravenously every day.
Because the drug cannot cross the blood-brain barrier, requiring repeated lumbar punctures.
Because the drug causes severe allergic reactions in most infants.
Why is administration of antisense oligonucleotide drugs for SMA complex?
Because the body rapidly metabolizes the drug before it reaches the CNS.
Because the drug must be administered intravenously every day.
Because the drug cannot cross the blood-brain barrier, requiring repeated lumbar punctures.
Because the drug causes severe allergic reactions in most infants.
Просматривай карточки здесь или sign up to study with spaced repetition.
Which drug is used for SMA treatment by binding to SMN2 pre-mRNA to favor correct splicing of exon 7?
Risdiplam
Просматривай карточки здесь или sign up to study with spaced repetition.
What is the primary limitation for the administration of the gene therapy Onasemnogene abeparvovec (Zolgensma) for SMA?
There is an upper weight limit of 20 kg because higher doses required for heavier children can cause toxicity.
Просматривай карточки здесь или sign up to study with spaced repetition.
What are the two major physical signs used to diagnose Marfan Syndrome related to hand and wrist manipulation?
The thumb sign and the wrist sign.
Просматривай карточки здесь или sign up to study with spaced repetition.
What is the typical arm span to height ratio observed in patients with Marfan Syndrome?
Lower than 1.0
Between 0.5 and 0.9
Higher than 1.4
Exactly 1.2
What is the typical arm span to height ratio observed in patients with Marfan Syndrome?
Lower than 1.0
Between 0.5 and 0.9
Higher than 1.4
Exactly 1.2
Просматривай карточки здесь или sign up to study with spaced repetition.
What is the molecular basis of Marfan Syndrome identified in 1991?
Mutations in the fibrillin gene FBN1.
Просматривай карточки здесь или sign up to study with spaced repetition.
What is the clinical significance of fibrillin (FB1) in the extracellular matrix?
It is important for linking elastin fibers and also has a functional relationship with TFbeta.
Просматривай карточки здесь или sign up to study with spaced repetition.
Besides the skeletal system, what are two other clinical signs associated with Marfan Syndrome?
Просматривай карточки здесь или sign up to study with spaced repetition.
How is the thumb sign performed to assist in the diagnosis of Marfan Syndrome?
The patient places the thumb within the palm and closes the other fingers; it is positive if the thumb last phalanx is protruding.
Просматривай карточки здесь или sign up to study with spaced repetition.
What is the most dramatic clinical manifestation of Marfan Syndrome that can lead to life-threatening complications?
Enlargement of the aorta, which can lead to aneurysms and dissection.
Просматривай карточки здесь или sign up to study with spaced repetition.
What is the primary mechanism of Allele-Specific PCR for detecting gene variations?
It uses specialized primers designed for a perfect match with a specific gene version; a perfect fit allows DNA replication and amplification, while a mismatch prevents it.
Why is 'multiplexing' advantageous in Allele-Specific PCR?
It allows multiple different mutations to be tested simultaneously in a single reaction, making the process highly efficient for routine screenings.
What is a major limitation of standard PCR in detecting heterozygous deletions?
It only detects duplications but not deletions.
The reaction is too slow to provide clinical results.
The normal allele amplifies even when the other allele is deleted, masking the deletion.
It requires too much DNA sample to be viable.
What is the current gold standard technique for detecting Copy Number Variants (CNVs)?
MLPA (Multiplex Ligation-dependent Probe Amplification).
How does MLPA identify specific exon deletions in a patient sample?
By comparing a patient's DNA profile against a standard control profile, identifying specific missing or reduced peaks in the test data.
Which form of Spinal Muscular Atrophy (SMA) is considered the most severe?
SMA1
SMA4
SMA0
SMA2
In SMA patients, what is the primary determinant of the phenotype's severity?
The number of SMN2 gene copies.
What is the consequence of the silent mutation present in the SMN2 gene?
It creates an exonic splicing site that causes transcripts to miss exon 7, resulting in only 5% of transcripts producing complete protein.
What specific challenge is encountered when counting SMN2 gene copies?
The physical arrangement of the copies is unknown; it is impossible to determine if copies are on one allele or both, preventing accurate genotype prediction in offspring.
What genetic condition is cited as a reason for using a highly targeted testing approach?
BRCA1-related breast cancer
SMA
Neurofibromatosis type 1
Achondroplasia
What is the recurrence risk for a child with SMA when both parents carry one SMN1 copy?
25%
What is the estimated recurrence risk for a child with SMA in the case of de novo mutations?
Low
Name two mechanisms of SMN gene rearrangement.
Why is the frequency of de novo rearrangements in SMA considered high for a recessive disease?
Genetic drift in modern populations.
High rates of environmental mutagen exposure.
The structure of chromosome 5q increases the risk of rearrangements that cause deletions in SMN1.
Polygenic inheritance patterns.
What does a '2+0' arrangement signify regarding SMN1 gene copies?
One chromosome has 2 copies of the gene and the other chromosome has 0 copies.
Why is the '2+0' SMN1 arrangement difficult to detect with standard screening?
Because the copies are located on different chromosomes entirely.
Because the standard test cannot distinguish between the presence of one gene on each chromosome versus two genes on a single chromosome.
Because the copies are silenced by methylation.
Because it occurs exclusively in males.
What is the primary limitation of population screening for SMN1 deletions regarding SMA subtypes?
It cannot predict the SMA subtype because the SMN2 copy number is unknown.
How are newborns screened for SMA in neonatal programs?
Through PCR amplifying the SMA region.
What is the difference between SMN1 and SMN2 regarding exon 7?
A nucleotide change in SMN2 abolishes an Exonic Splicing Enhancer (ESE) and favors an Intronic Splicing Silencer (ISS), leading to the skipping of exon 7.
What is the function of the drug Spinraza in treating SMA?
It is an antisense oligonucleotide that binds to an intronic splicing silencer, preventing the skipping of exon 7 and restoring functional protein production.
Why is administration of antisense oligonucleotide drugs for SMA complex?
Because the body rapidly metabolizes the drug before it reaches the CNS.
Because the drug must be administered intravenously every day.
Because the drug cannot cross the blood-brain barrier, requiring repeated lumbar punctures.
Because the drug causes severe allergic reactions in most infants.
Which drug is used for SMA treatment by binding to SMN2 pre-mRNA to favor correct splicing of exon 7?
Risdiplam
What is the primary limitation for the administration of the gene therapy Onasemnogene abeparvovec (Zolgensma) for SMA?
There is an upper weight limit of 20 kg because higher doses required for heavier children can cause toxicity.
What are the two major physical signs used to diagnose Marfan Syndrome related to hand and wrist manipulation?
The thumb sign and the wrist sign.
What is the typical arm span to height ratio observed in patients with Marfan Syndrome?
Lower than 1.0
Between 0.5 and 0.9
Higher than 1.4
Exactly 1.2
What is the molecular basis of Marfan Syndrome identified in 1991?
Mutations in the fibrillin gene FBN1.
What is the clinical significance of fibrillin (FB1) in the extracellular matrix?
It is important for linking elastin fibers and also has a functional relationship with TFbeta.
Besides the skeletal system, what are two other clinical signs associated with Marfan Syndrome?
How is the thumb sign performed to assist in the diagnosis of Marfan Syndrome?
The patient places the thumb within the palm and closes the other fingers; it is positive if the thumb last phalanx is protruding.
What is the most dramatic clinical manifestation of Marfan Syndrome that can lead to life-threatening complications?
Enlargement of the aorta, which can lead to aneurysms and dissection.
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