Quiz II Review Flashcards
What is this explaining? Given that someone has inherited the mutant allele, what is the chance that they will express the phenotype…
Penetrance
What is this explaining? Given that a person who has inherited a mutant allele expresses the trait, how severely affected are they?
VE…Variable Expressivity
What types of disorders exhibit ANTICIPATION?
Repeat Expansion Disorders
What type of disorder shows increased severity and/or decreased age at onset in successive generations? What is the term used to describe this disorder?
Repeat Expansion Disorder….Anticipation
What type of disorder reflects increased number of repeats as passed from generation to generation?
Repeat Expansion Disorders
What is differential modification and expression of alleles of a gene depending on the sex of the parent of origin?
Imprinting
What are the two main examples of IMPRINTING?
Prader-Willi=Father….Angelman=mother
What are these TWO BIG clues related to? 1. Association of Uniparental Disomy (UPD) with abnormal development 2.Association of consistent parental origin of mutant allele in inherited disorder
Imprinting
_______ allele usually refers to silent, inactivated allele
Imprinted
What is the inheritance of 2 copies of a gene or chromosome from 1 parent?
Uniparental Disomy
What mechanism has implications for recessive disorders and imprinted disorders in which it was first described in a child with cystic fibrosis; only the mother was a carrier? It si also very important for PWS and AS…
Uniparental Disomy
Who do you receive your mitochondrial DNA from?
jo mamma!
Does mitochondrial DNA have histones?
Nope
What is the term used in mitochondrial genetics where you can have BOTH wild type AND mutant mitochondrial DNA?
HeteroPlasmy
What is the term for the DOSE load of mutant DNA must meet a certain level before the phenotype is expressed?
Threshold effect
Mutation Nomenclature: p.Gly17Arg
(p.=protein)….aa substitution, missense
Mutation Nomenclature: p.Gly17*
stop codon, nonsense
Mutation Nomenclature: p.Leu6Hisfs*3
frameshift mutation due to insertion or deletion of 1 or 2 nucleotides
Mutation Nomenclature: c.101-2A>T
splicing mutation of intron
What kind of mechanism is Achondroplasia? What happens with the Homozygous form?
Autosomal Dominant…its leathal
What is the most common form of intellectual disability?
fragile X
What happens when a PT testing for fragile X does not show ANY markers on PCR?
the patient has more then 100 repeats of the gene and is therefore going to need a SOUTHERN BLOT. the chances of the patient being affected by intellectual disability are very high.
What are the two mechanism of inheritance in achondroplasia?
Autosomal Dominant or Incomplete Dominance
In Achondroplasia, De Novo mutations are ALWAYS passed down by the ______. WHAT % are De Novo?
FATHER….NOT THE MOTHER…90% of Achondroplasia is caused by a De Novo mutation
What are the 4 disorders associated with TriNucleotide Repeats??
1.Fragile X 2. Huntington Disease 3.Freidreich Ataxia 4.Myotonic Dystrophy
What is the Nucletoide repeat for Fragile X? Where is it found?
CGG….found in the 5’ UTR region
What is the nucleotide repeat for Huntington’s Disease? Where is it found?
CAG (polyGlu)….on the Exon
What is the nucleotide repeat for Freidreich Ataxia? Where is it found?
GAA….intron
What is the nucleotide repeat for Myotonic Dystrophy? Where is it found?
GTG…in the 3’UTR region
What is the ONLY Autosomal Recessive disorder that is related to Trinucleotide repeats?
Fredreich Ataxia
Which disorder has a trinucleotide repeat of CGG in the 5’UTR region?
Fragile X
Which disorder has a trinucleotide repeat of CAG in the coding region?
Huntington’s Disease
Which disorder has a trinucleotide repeat of GAA in the intron?
Freidreich Ataxia
Which disorder has a trinucleotide repeat of GTG in the 3’ UTR region?
Myotonic Dystrophy
T of F: A De Novo mutation can for Achondroplasia can be passed down by the mother.
FALSE. ITS ALWAYS THE FATHER.
What 2 methods do we use to diagnose Achondroplasia?
1.PCR & 2.Restriction Enzyme Digestion
What disease is associated with the most mutable nucleotide in the human genome?
Achondroplasia
If a Pt showing signs of Fragile X has a PCR done and it does not read, they are more then 100 repeats. Are they intellectually disabled?
Not necessarily. 150 repeats is a mutant carrier…200 or more is phenotypic
What will happen in a Fragile X MALE that is a mutant carrier, but is not intellectually disabled?
PD like symptoms with age
What will happen in a Fragile X FEMALE that is a mutant carrier, but is not intellectually disabled?
Premature Ovarian Failure (early menopause)
What are the three ways Uniparental Disomy can occur? Which is the most rare?
1.Trisomy Rescue 2.Monosomy Rescue 3.Gamete Complement…Gamete complement is the most rare…it requires non disjunction in BOTH male and female
What chromosomes are the only viable autosomal trisomys?
13,18,21 only 21 is long term life
What is the only viable monosomy?
45X (turner syndrome)
What is the term for the mitochondrial DNA being transcribed in one big chunk?
Polycistronic
What type of product is made with the dominant disorder haplodeficiency?
Normal Product, but HALF the amount…no phenotypic result
