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Cytogenetics and Chromosomal Analysis Flashcards

7 cards from real ABMGG practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

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  1. The Philadelphia chromosome, found in chronic myelogenous leukemia (CML), results from which chromosomal rearrangement?

    Answer: Reciprocal translocation t(9;22)(q34;q11.2)

    The Philadelphia chromosome is formed by t(9;22)(q34;q11.2), which fuses BCR on chromosome 22 with ABL1 on chromosome 9 to create the oncogenic BCR::ABL1 fusion gene.

  2. A pericentric inversion involves a chromosomal segment that:

    Answer: Spans the centromere, including both arms

    A pericentric inversion includes the centromere, with breakpoints in both the short (p) and long (q) arms, potentially changing the chromosome's arm ratio.

  3. A carrier of a balanced reciprocal translocation is at risk of producing offspring with which abnormality?

    Answer: Offspring with unbalanced chromosomal segments causing partial monosomy or trisomy

    During meiosis, a balanced translocation carrier can produce unbalanced gametes through 3:1 or 2:2 segregation, resulting in offspring with partial monosomy or partial trisomy.

  4. Chromosomal mosaicism in a patient is BEST defined as:

    Answer: The presence of two or more cytogenetically distinct cell lines from the same zygote

    Mosaicism is the coexistence of two or more cell populations with different chromosomal constitutions arising from a single zygote, typically due to a post-zygotic mitotic error.

  5. Uniparental disomy (UPD) can cause disease even when both copies of a chromosome are structurally normal primarily because of:

    Answer: Genomic imprinting causing silencing of maternally or paternally imprinted genes

    Genomic imprinting silences certain genes depending on parental origin; UPD can result in either two silenced (imprinted) copies or two expressed copies, disrupting normal gene dosage for imprinted loci.

  6. Array comparative genomic hybridization (aCGH) detects copy number variants (CNVs) by comparing:

    Answer: Hybridization intensity of patient DNA vs. a reference DNA on oligonucleotide probes

    In aCGH, differentially labeled patient and reference DNAs are co-hybridized to probes on a microarray; the ratio of fluorescence intensities reveals gains (duplications) or losses (deletions) in the patient.

  7. Spectral karyotyping (SKY) and multicolor FISH (M-FISH) are especially useful for identifying:

    Answer: Complex chromosomal rearrangements and marker chromosomes of unknown origin

    SKY/M-FISH uses combinatorial labeling with multiple fluorochromes to paint each chromosome a unique color, making it ideal for characterizing complex rearrangements and small marker chromosomes.