Genetic Testing Flashcards
Genetic Testing, is it just for diagnosis?
No
Predisposition or diagnosis
Genetic Testing, always DNA?
No,
could be biochemical or genetic markers
What would be a good test for Trisomy 21?
Chromosomal analysis
_____________ is useful for identifying aneuploidies, and is also suitable for IDing large structural changes (duplication, deletion, rearrangement)
Chromosome analysis
What is the resolution of chromosome analysis
3-5Mb
What would be a good test for WAGR? interstitial deletion of 11p13 Wilms tumor Aniridia Genitourinary malformation Retarded
Chromosome analysis because deletion is bigger than 3Mb
What is WAGR syndrome
Cause consequence
Deletion 11p13 Wilms tumor Aniridia Genital malformation Retarded
Although we could use Chromosomal analysis for WAGR what would be another approach?
FISH for PAX6 locus in child with WAGR
What is required in FISH?
You must know what you are Fishing for
E.G. if you know that a region is deleted (like PAX6 in WAGR) you can design a probe for PAX6 and look for it’s absence
What is the resolution of FISH
200KB
If you know, or strongly suspect the diagnosis of a micro-duplication or deletion syndrome, then ________may be your best bet
FISH
When you do not know the diagnosis, would FISH be good?
No, you don’t know what your Fishing for
Consider a genomic test
CMA
Test and reference DNA samples (targets) are labeled with different colors, mixed, and passed over an array with (oligonucleotide probes) containing DNA fragments from the whole genome - abnormal ratios of colors are indicative of deletions / duplications
Spots on array have known addresses :)
Lie FISH on steroids
How can we use CMA to determine gene involvement?
Narrow down to smallest possible region (deleted or duplicated) that is present in every patient presenting with phenotype
Which study is ideal for looking at the sequence of a known disease gene?
DNA sequencing analysis
