Medical Genetics Flashcards
Trisomy 21 (down syndrome) is an example of what kind of genetic disorder?
Chromosome disorder
Turner syndrome (45X) is what kind of genetic disorder?
Chromosome disorder
A single gene is changed from its normal form, usually resulting in dysfunctional protein in this type of genetic disorder
Single-gene disorder
Hemophilia and cystic fibrosis are what kind of genetic disorder?
Single-gene disorder
Independent mitochondrial DNA is altered in this genetic disorder?
Mitochondrial disorders
LHON (Leber hered. optic neuropathy) and MERRF (myoclonic epilepsy with ragged red fibers) are what kind of genetic disorder?
Mitochondrial disorders
How much of the human genome is dispersed repetitive DNA?
45%
Long interspersed elements of up to 7000 bp
LINEs
Short interspersed elements between 90 and 500 bps
SINEs
A type of SINE, about 300 bp long that can be excised and inserted into other parts of the genome
Alu repeats
tandem repeats clustered in certain locations within the chromosome, makes up about 10% of the human genome
Satellite DNA
Meiosis I. Two haploid cells are formed from a diploid cell. Centromeres intact, but homo chromosomes seperate
Reduction division
Meiosis II. Each haploid cell is replicated, centromeres divide.
Equational division
Chiasmata for formed during what part of cell division?
Prophase I
Synapsis occurs during what part of the cell divsion?
Prophase I
Two chromosomes in a unit is called what?
Bivalent
Four chromatids in a unit is called what?
Tetrad
A single nucleotide is replaced by a different one is what kind of mutation?
Single base mutation
Change in splice site which results in part of the intron remaining within the mature mRNA is what kind of mutation?
Splice site mutation
Change resulting in creation of a donor site in an intron can result in the inclusion of intron sequence in mature mRNA is what kind of mutation?
Splice site mutation
Change resulting in creation of a donor site in an intron can result in exon skipping in mature mRNA is what kind of mutation?
Splice site mutation
This mutation causes a change in expression, usually by affecting ability of RNA polymerase to bind
Promoter mutation
Guillian-Barre syndrome has an extra AT in TATA box, which reduces the expression by 80%, because of this type of mutation?
Promoter mutation
Addition or removal of bases from a sequence results in this type of mutation?
Deletion or Insertion mutation
Small deletion/insertion of bases causing a change in the reading from (not a multiple of 3)
Frameshift mutation
Mobile genetic element inserts in or near a gene, altering expression
Transposon
trinucleotide runs of AA’s that occur in normal range of repeats (lengthens)
Expanded repeat
Huntington’s disease is due to what kind of mutation?
Expanded repeat
A protein has a new enhanced specificity or becomes constitutively active after a mutation is called what?
Gain of function
An active site has mutated causes this result in the binding protein
Loss of function
Structural mutation of Glutamate 6 to Valine results in this disease
Sickle Cell anemia
Thalassemias are a result of what kind of mutation?
control of expression mutation (not making enough of a globin form)
A patient with excess beta-globin, forming B-globin tetramers has what type of Thalassemia?
Alpha Thalassemia
A patient is diagnosed with alpha-globin tetramers and is suffering from this type of Thalassemia anemia
Beta Thalassemia
A patient is exposed to low energy particles that shift electrons causing chemical reactions between bases forming pyrimidine dimers. This is due to what kind of radiation?
Nonionizing radiation
What size of gene is more likely to develop a mutation?
Large genes
Why is the age of parents a factor in genetic disease passed to offspring?
Older parents have more mutations in the germ cells being passed to offspring
CpG dimers that are usually methylated act as what in affecting the rate of mutation?
Hot spots
Xeroderma pigmentosum disorder is a defect in what kind of DNA repair mechanism?
NER
What is the Hardy-Weinberg equation?
p^2 + 2pq + q^2 = 1
In a randomly mating population, one would use this equation to estimate the frequency of gene variants
Hardy Weinberg equations
Isolated populations change with time due to different pressures and random events. This results in populations that are genetically different from other populations
Genetic drift
Intermixing of populations, which introduces new alleles and mutations
Gene flow
A small number of individuals start a population, gene frequencies no longer reflect larger populations
Founder effect
A single gene copy of allele causes phenotype. Usually single affected parent, no skipped generations and 50% of offspring is affected. Very rare, 1 in 1000 people
Autosomal dominant disorder
Retinoblastoma, Achondroplasia, and Postaxial polydactyly are examples of what kind of inheritance disorder?
Autosomal dominant disorder
Results from the mating of two carriers. May skip a generation with males and females equally affected.
Autosomal recessive disorder
Albinism is what kind of inherited disorder?
Autosomal recessive
Cystic fibrosis is what kind of inherited disorder?
Autsomal recessive
Mutation occurs during embryonic period that effects germline cells, but not somatic cells. Offspring present in odd proportions and in very unlikely pedigree.
Germline mosaicism
Huntington’s disease complicate inheritance patters due to what factor?
Delayed age of onset
Person with disease does not present with complete phenotype, Retinoblastoma is an example of this
Reduced penetrance
Multiple effects result from one mutation (single gene effects multiple tissues)
Pleiotropy
Marfan’s Syndrome is an example of what kind of inheritance pattern?
Pleiotropy
Hemoglobin derived diseases are a result of what kind of inheritance pattern?
Allelic heterogeneity
Multiple genes effect a single pathway, as in urea cycle defects are what kind of inheritance pattern?
Locus heterogeneity
Genes expressed only on paternal or maternal transmitted chromosomes show what kind of inheritance pattern?
Genomic imprinting
Dominant disorders that are more severe in later generations OR age-delayed disorders that present earlier in later generations are an example of what kind of inheritance pattern?
Anticipation
Mating of related persons resulting in recessive disease is what kind of inheritance pattern?
Consanguinity
A child presents with Huntington’s chorea. This is due to what type of inheritance pattern?
Anticipation
