Pathology L09 Chromosomes in Health and Disease Flashcards Preview

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Flashcards in Pathology L09 Chromosomes in Health and Disease Deck (16)

What is a karyotype?

Chromosomal constitution of an individual


What are 2 advantages and 2 disadvantages of conventional cytogenetics?

ADV: High sensitivity/specificity AND detects both numerical and structural anomalies
DISADV: Tissue culturing required AND labour intensive analysis


What are 2 advantages and 2 disadvantages of FISH?

ADV: Culture not required for interphase FISH AND numerical and structural anomalies detected
DISADV: Interrogates small regions AND must know what you are looking for beforehand


What are 2 advantages and 2 disadvantages of chromosomal microarray?

ADV: Culture not required, can visual homozygous regions using SNP genotyping and can detect submicroscopic number changes across genome
DISADV: Expensive and no structural information provided


What is the structure of an acrocentric chromosome?

Short arm (p) almost missing – very small compared to long arm (q)


What is this karyotype nomenclature describing? 46, XX, t(11;22)

Female with normal chromosome number but a translocation between one homologue of chromosome 11 and one homologue of chromosome 22


What is the mechanism for numerical chromosomal aberrations?

Nondisjunction during meiosis or mitosis


What is the difference between euploidy and aneuploidy?

Euploidy has a number of chromosome that is a multiple of the haploid number whereas number of chromosomes in aneuploidy are not divisible by haploid number


What are 3 trisomy’s that are compatible with birth?

21 (Down), 18 (Edward), 13 (Patau)


Describe the features of Robertsonian translocation?

Merging between 2 acrocentric chromosomes
Balanced carries have 45 chromosomes
Carriers phenotypically normal as they have the same amount of genetic material
Risk for a live born child with unbalanced rearrangement
Usually occurs with chromosomes 13, 14, 15, 21 & 22


Which form of ‘inversion’ of a chromosome involves the centromere?



What is the mechanism for non-allelic homologous recombination?

Chromosomal breakage and reunion mediated by low copy repeats. LCR’s are highly homologous sequence elements scattered through the genome and result in both copy number variations and chromosomal rearrangements


Which genetic alteration causes DiGeorge/Velocardiofacial syndrome?

22q11.2 microdeletions


Why is it important to determine whether NSCLC is caused by an ALK gene rearrangement?

Patients with this rearrangement have much better survival rates when treated with Crizotinib


What is the main difference between mosaicism and chimera?

Mosaicism are multiple cell lineages from ONE fertilized egg whereas chimeras have cells from multiple zygotes.


What are breakpoint regions of chromosomes rich in?

A&T-rich inverted repeat sequences

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