Flashcards in Genetic Lab Diagnostics Deck (15)
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1
Chromosome Analysis Prep Process (4)
Culture cells on mitosis stimulating medium, arrest in metaphase w/ colcemid, then treat w/ KCl and centrifuge out chroms
2
5 Common Sources of Chromosomes
Lymphocytes (blood)
Fibroblasts (skin)
Amniocytes
Bone marrow
Placental tissue
3
2 G Bands
Dark bands (G+) are AT rich and gene poor
Light bands (G-) are GC rich and gene rich
4
Band Numbering
From centromere to telomere along each p and q arm
5
3 Things to Give Chromosome Location of a Gene
Regions
Bands
Sub-bands
6
4 Indications to Request a G-Band Chrom Analysis
Recurring miscarriages/stillbirths
Infertility (before invasive fertilization techniques)
Immediately when Down/Turner/Klinefelter syndrome or autosomal trisomy suspected
Characterization of malignant tumors
7
Basic Form of Karyotype Nomenclature
[Total # of Chromsomes], [sex chromosomes], [variation acronym]([chrom #]),([arm][region][band].[sub-band])
8
Pericentric Inversions (3)
Creates a loop
Has 5-10% risk of unbalanced inversion for progeny (depending on size of inversion)
Partial duplication/deletions in the 2 imbalanced chromosomes
9
FISH Benefits (2)
Can see smaller microdeletions than G-band
Can rapidly diagnose aneuploidys
10
Microarray Benefit
Can detect nearly any unbalanced structural abnormality so often first genetic test done
11
Oligoarray vs. SNP array
Oligo tests all loci for all well-known micro del/duplication syndromes
SNP even better, detects uniparental disomy and regions of homozygosity (consanguinity)
12
6 Things Microarray Doesn't Test for
Low-level mosaicism
*Balanced rearrangements (karyotype for that)
Small dels
Small dups
Point muts
Triplet repeat extensions
13
Copy Number Variant (CNV)
Del or dup of whole gene too small to be detected on karyotype
14
How to tell if CNV Causative of a Gene or just familial?
Test parents and see if they have it too/have the phenotype
15
