Molecular Diagnostics Flashcards
6 cards from real ASCP practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 6 Molecular Diagnostics flashcards as text
In real-time PCR (qPCR), what does the Ct (cycle threshold) value represent?
Answer: The cycle at which fluorescence crosses a threshold above background
The Ct value is the PCR cycle number at which the fluorescence signal from a sample crosses a predefined threshold above background noise. Lower Ct values indicate more target DNA present. Higher Ct values indicate less target DNA.
Which molecular technique is used to detect chromosomal translocations such as t(9;22) (BCR-ABL) in CML?
Answer: FISH and RT-PCR
Both FISH (fluorescence in situ hybridization) and RT-PCR (reverse transcription PCR) are used to detect t(9;22). FISH detects the chromosomal rearrangement; RT-PCR detects the BCR-ABL1 fusion mRNA and is used for quantitative minimal residual disease monitoring.
BRCA1 and BRCA2 are tumor suppressor genes involved in DNA repair. Mutations in these genes primarily increase the risk of:
Answer: Breast and ovarian cancer
Pathogenic variants in BRCA1 and BRCA2 confer significantly elevated lifetime risk of breast cancer (approximately 70%) and ovarian cancer (approximately 44% for BRCA1, approximately 17% for BRCA2). BRCA2 also elevates pancreatic and male breast cancer risk.
Which of the following best describes next-generation sequencing (NGS)?
Answer: Massively parallel sequencing of millions of DNA fragments simultaneously
NGS (also called massively parallel sequencing) sequences millions of short DNA fragments simultaneously, providing high throughput and depth of coverage unavailable with Sanger (first-generation) sequencing.
Methylation-specific PCR (MSP) is used to detect which epigenetic modification?
Answer: DNA cytosine methylation at CpG sites
MSP detects DNA methylation at CpG dinucleotides. Bisulfite treatment converts unmethylated cytosines to uracil (read as thymine after PCR), while methylated cytosines are protected. MSP primers distinguish methylated from unmethylated alleles.
Fragile X syndrome is caused by expansion of which mutation in the FMR1 gene?
Answer: CGG trinucleotide repeat expansion in the 5' UTR
Fragile X syndrome results from more than 200 CGG trinucleotide repeats in the 5' UTR of FMR1, causing hypermethylation and gene silencing. Normal is 5–44 repeats; premutation is 55–200 repeats; full mutation is above 200 repeats.