Lecture 4: Genetic Mutations/Disorders Flashcards
(48 cards)
Autosomal Mutations occur in … cells and are not …. , while Germline mutations occur in … cells and may be …
Autosomal Mutations occur in SOMATIC cells and are not INHERITED, while Germ-line mutations occur in GAMETIC cells and may be INHERITED
When naming mutations/variants what is denoted as the +1 position?
The “A” of the Start Codon (AUG)
Describe the Intron Mutation–> c89+21
c89 refers to the last exon nucleotide (Exon 89) and the mutation occurs 32 nucleotides into the Intron
How would you write the Amino Acid mutation Tryptophan to Lysine at the 108th position (in AA single abbreviation)?
P. W108K
What type of mutation is P. Asp47X
Missense Mutation (X refers to an improper STOP codon)
What are the three STOP codons
1) UGA 2) UAA 3) UAG
In a …. Insertion/Deletion the Open Reading Frame (ORF) is changed, whereas in a …. Insertion/Deletion the ORF is not changed
Frameshift; Non-Frameshift
What is the single point mutation of Sickle Cell Anaemia?
P. G6V of the Beta-Subunit of Haemaglobin
True or False: A Missense Mutation results from an early Stop Codon, while a Non-Sense Mutation results from a Substitution of different AAs.
False; A NON-SENSE Mutation results from an early Stop Codon, while a MISSENSE Mutation results from a substitution of different AAs.
Define Non-Sense Mediated Decay
A Non-Sense mRNA mutation is recognized by a surveillance pathway within the cell and the Non-sense mRNA is degraded prior to translation.
What two nucleotides does an Intron typically start and end with?
Introns typically start with “GU” and end in “AG”
What mutations cause Neurofibromatosis Type 1 (NF1) and/or Menkes Disease?
Splice Site Mutations
True or False: Splice Site Mutations lead to 1) New Splice Sites 2) Unmasking of Cryptic Splice Sites
True
A missense mutation of the …. gene is responsible for Achondroplasia (i.e. “Dwarfism”).
FGFR gene on Chromosome 4 (c. 113 G > A)
The FGFR gene is an example of a (Gain/Loss) of Function mutation as it (Over-inhibits/Under-inhibits) Cartilage formation, leading to Achondroplasia
Gain of Function Mutation; Over-inhibits Cartilage Formation
True or False: An individual homozygous for the gene mutation of Achondroplasia is even shorter that an individual that is only heterozygous?
False; The homozygote form of Achondroplasia (both mutant FGFR gene copies) is lethal.
What three organ systems does Marfan Syndrome affect?
1) Skeletal 2) Occular 3) Cardiovascular
What is Pleitropy? What disease/syndrome is an example of Pleitropy?
One gene affects multiple organ systems in the body (Ex. Marfan Syndrome)
What phenotype does someone with Marfan Syndrome have?
Extremely tall, potentially dislocated lens of the eye and aortic dissection
The … gene on Chromosome 15 is responsible for Marfan Syndrome and is an example of a (Gain/Loss) of Function mutation.
The FB1N gene on Chromosome 15 is responsible for Marfan Syndrome and is an example of a LOSS of Function mutation.
How does a mutation in FB1N lead to Marfan Syndrome?
- FB1N encodes for Fibrillin Protein which is a major component of Microfibrils
- Microfibrils 1) Provide Structure 2) Control free TFGBeta
- TGFBeta is a potent Growth Factor and in excess can lead to the severe problems associated with Marfan Syndrome
Ex. Extremely tall, Aortic Dissection and Lens of the Eye Dislocations
True or False: An increase in Maternal age leads to an increase in De Nova Mutations for Marfan Syndrome and Achondroplasia
False; An increase in PATERNAL age leads to an increase in De Nova Mutations for Marfan Syndrome and Achondroplasia
True or False: The FB1N gene is a Loss of Function mutation and the FGFR gene is a Gain of Function mutation
True; FB1N mutation= Loss of Function= Marfan Syndrome
FGFR mutation= Gain of Function= Achondroplasia
What are three clinical signs for diagnosis of Cystic Fibrosis (CF) in babies?
1) Meconium Illeus (Inability to pass Black Meconium)
2) Poor Fat Absorption (Leads to a Deficiency in Pancreatic Enzymes)
3) Pulmonary Problems (#1 reason for deaths)
