Prep for USMLEPrep for USMLE
         Forum      |     Resources New Posts   |   Register   |   Login





 Genetic tests and mutations  



Post Reply  
  • 0/5
  • 1
  • 2
  • 3
  • 4
  • 5


Author3 Posts
  #1

Hello,

I have a hard time figuring out the answers for the passage below. Thank you for your inputs.

Le fou

Many different mutations in the gene BRCA1 confer hereditary susceptibility to breast and ovarian cancer. The gene is very large, within a region spanning 81,000 nucleotide pairs. It encodes a protein that suppresses the formation of cancerous tumors. Of the 27 mutations listed in the OMIM entry for this gene, 22 are insertion, deletion, or nonsense mutations that create premature termination codons. No particular mutant allele is especially prevalent in human populations when compared to other mutant alleles.

1)
Given the structure of the BRCA1 gene and the distribution of mutations, which of the following tests is the most reliable for detection of mutations in the BRCA1 gene in a genetic testing program?

a) RFLP testing
b) Microsatellite polymorphism testing
c) DNA fingerprinting
d) DNA sequencing
e) VNTR testing
f) EST testing
g) trinucleotide-repeat expansion testing

I am hesitating between a, b, d or f but I think that d is the right answer. Can anybody explains to me what they think the right answer is?

2)
Nearly all of the mutations have been discovered in cancer patients or in people with a family history of breast or ovarian cancer. What does this observation indicate about the predominance of premature termination codons in the mutant sequences?

a) The gene is more likely to undergo deletion and insertion mutations
b) Mutant alleles with premature termination codons are more likely to encode nonfunctional products than are mutant alleles with substitution mutations
c) DNA sequencing is more prone to detect deletion, insertion, and nonsense mutations than substitution mutations

Here, I have no clue! Can you help me out?





  #2

1. b) also called SNP. the best to test with when you know what you're looking for.

2. b) the correct one. choice a) there is not much known about cancer genes to conclude that. choice c) DNA sequencing is the most sensitive technique and can detect all listed.



  #3

Thank you for your reply.

For #1, I thought that we don't know what we are looking for since it says"No particular mutant allele is especially prevalent in human populations when compared to other mutant alleles." Can you explain?

Thanks,

Le fou






Bookmark and Share



This thread is closed, so you cannot post a reply.



Login or Register to post messages








show Similar forum topics

mutations
missense mutations
splice donor/splice acceptor mutations
show Related resources

Blueprints in Obstetrics and Gynecology
Human Anatomy and Physiology GC 1132
Kaplan Lecture Notes and Qbank








Advertise | Support | Premium | Contact