GDM Quiz #1

How many bp’s are there in a megabase?

1,000,000 base pairs!

Which mutation would a karyotype be able to detect?

A six megabase deletion

Which mutation would likely be the most detrimental to the protein product of a 10-exon gene?

A splice site mutation at intron 2

In what way are microarrays better for detecting microdeletions than FISH arrays?

Microarrays specialize in detecting CNVs w/o requiring a suspect gene/syndrome

What is a primary difference between frameshift mutations and splice site mutations?

Splice site mutations alter pre-mRNA splicing mechanisms, while frameshift mutations alter the ribosome reading frame during translation.

T/F: Klinefelter’s (XXY) is inheritable, and any parent with this syndrome planning for IVF should be notified.

False; it’s generally a De Novo mutation

Cat’s Eye Syndrome is caused by what mutation event on chromosome 22?

A duplication event at 22q11

Which of the following accurately describes the relationship among a genetic variant, a mutation, and a polymorphism?

A variant is an umbrella term for any DNA sequence change, while mutations and polymorphisms are subcategories separated by population frequency and functional impact.

What is the population frequency threshold used to distinguish a polymorphism from a rare variant or mutation?

1%

Which of the following is true regarding Sickle-Cell mutations

They are caused by a single missense mutation in the HBB gene

Which of the following is NOT true regarding Cystic Fibrosis?

It can be caused by a deletion of a single base pair in F508

Which of the following is true about the lysosomes?

It is the garbage bag of the cell

Which is FALSE regarding splice donors and splice acceptors?

Donors and acceptors are two names for the same location.

Tay-Sach’s Disease is primarily caused by a mutation in what gene?

Frameshift or deletion HEXA gene mutations, chromosome 15

T/F: Dysfunction of the HEXA gene leads to the buildup of gangliosides in the lysosome.

TRUE

Which of the following is FALSE regarding the HEXA complex?

Each component (α, β, and the activator) are all encoded by chromosome 15

Which of the following is TRUE regarding the inheritance of Tay-Sachs?

It is inherited in a autosomal recessive fashion

What is NOT a primary difference between Tay-Sach’s and Pompe Disease?

Tay-Sach's is a lysosomal disorder, whereas Pompe Disease affects the Sarcoplasmic Reticulum.

Which of the following is TRUE regarding treatment for Pompe Disease?

Exogenous enzymes break down naturally within the lysosome and cannot replicate themselves.

Which of the following is NOT a possible symptom of 22q11.2 deletion syndrome

Hypercalcemia (High blood calcium)

You have a patient with a 17p11.2 deletion, which disorder do they have?

Smith-Magenis syndrome

You have a patient with a 17p11.2 DUPLICATION, which syndrome do they have?

Potocki-Lupski syndrome

In Smith-Magenis syndrome, which of the following is TRUE regarding the RAI1 gene?

RAI1 encodes a transcription factor that regulates the Circadian Clock genes.

What is the primary cause of Angelmann Syndrome?

Large Deletions

T/F: Deletion/Dupe size within a gene has no effect on the severity of the phenotype

FALSE; size of the mutation generally has a positive correlation to phenotype severity

What is NOT a function of UBE3A?

It's motor protein that transports neurotransmitter vesicles along axonal microtubules.

T/F: DiGeorge and Cat’s Eye Syndrome are both caused by different mutations in the same gene?

TRUE; mutation in the 22q11 region

T/F: Low copy repeat regions cause mistaken crossovers, causing duplications and deletions due to false sequence homology.

TRUE

T/F: 15q11.2 duplication is caused by an extra PATERNALLY derived copy of PWACR

FALSE; Maternal

Potocki-Lupski Syndrome (17p11.2 dupe) is characterized by the following EXCEPT:

Extremely distinguishable facial characteristics

Coloboma is defined as what?

Missing tissue from the eye at birth

T/F: Short sleep periods, learning disabilities, and motor disabilities are all symptoms of Angelmann Syndrome

TRUE

T/F: The paternal copy of UBE3A is not expressed, meaning that deletion of the maternal copy is detrimental.

TRUE

Which of the following is FALSE regarding Microarrays?

They can detect duplications smaller than 500kb