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136 Cards in this Set
- Front
- Back
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What is genetics?
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The field of science that looks at how traits (such as eye color) are passed down from parents to their children through genes
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What is the genome?
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The totality of the approximately 25000 genes that humans have in their genetic make-up.
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genes are contained in ___
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chromosomes
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Chromosomes are located within the ____ ____
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cell nucleus
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__ __ is a display of its genome, revealing all the chromosomes present in an individual.
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Human Karyotype
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__ pairs of chromosomes are autosomes.
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22
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One pair of chromosomes is a __ chromosome.
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Sex
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Humans carry __ to __ genes, which are composed of DNA.
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20,000-25,000.
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What are the 4 chemicals that compose DNA
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-Adenine
-Thymine -Cytosine -Guanine |
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Each individual gene is made up of a segment of __
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DNA
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DNA contains genetic instructions for making ___ needed for proper functioning.
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proteins
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Genome = ___ chromosomes and approximately __ __ base pairs
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46; 3 billion
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What is the definition of a hereditary mutation?
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-gene defects that are passed from a parent to a child. Hereditary mutations are present in the egg or sperm that join during fertilization and develop into a fetus
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What is an acquired mutation?>
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Most cancers are caused by DNA changes that are acquired during the persons's life. These are called acquired, sporadic or somatic mutations. These can be caused by thing in the environment such as exposure to UV radiation or toxins
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Only __% of the genome provides the set of instruction called genes that are used to build the body's protein.
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3
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the regions in the genome that provide the instructions for protein production are called the __ __
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coding regions
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Close to each gene are __ __ of DNA which are able to turn the gene on or off
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regulatory sequences
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The ___ project, completed by hundreds of scientists from dozens of labs around that world, reveal that __% of the human genome serves some purpose and is biochemically active.
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ENCODE; 80%
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What is the human genome project?
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an international effort that began in oct 1990 and completed in 2003
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what were the 3 goals of the HGP?
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1. Determine the complete sequence of the 3 billion DNA subunits
2. Identify all human genes 3. To generate a resource that could be used for a broad range of biomedical studies. Look for the genetic variation that increase risk for specific diseases, such as cancer |
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THe __ describes haplotypes, including their __ in the genome and how common they are in different populations throughout the world
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HapMap; locations
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What is the HapMap?
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a catalog of single nucleotide polymorphisms. when several SNPs cluster together on a chromosome, they are inherited as a block known as a haplotype
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What did the results of ENCODE show?
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that many DNA variants previously correlated with certain diseases lie within or very near non-coding functional DNA elements, providing new leads for linking genetic variation and disease
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What are the key concepts of genetic variation-latent effects?
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-over time in the context of infections, environmental exposures, they alter a persons risk for cancer
-explain why one person responds to drug while another doesn't -affect each person's susceptibility to the damaging effects of carcinogens |
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ToF: chromosomes can undergo translocations.
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True
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Mutations alter genes __ for its corresponding proteins
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instructions
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In terms of mutations, how does cancer develop?
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when many variations occur in critical genes within the same cell
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Describe the CML translocation
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Occurs between chromosome 9 and 22 creating a fusion gene called Bcr-Abl that produces a protein (tyrosine kinase) thought to promote development of leukemia
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ToF: persons with cancer susceptibility genes carry altered alleles in every cell in their bodies.
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True
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Which chromosomes are effected by BRCA 1 and 2 and what is the transmission type?
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1. chrom 17 autosomal dom
2. Chrom 13 autosomal dom |
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ToF: most hereditary cancer syndromes are inherited in autosomal recessive fashion?
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false: dominant
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What is complete penetrance?
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an individual carries a single copy of a dominant allele, the trait will be expressed. (genotype=phenotype)
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What is incomplete penetrance?
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Some individuals fail to express the trait even though they carry the allele
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ToF: SNPS can cause silent, harmful or latent effects
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True
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Cancer researchers believe that in addition to inherited or acquired mutations, __ may play a role in cancer.
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SNPs
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ToF: SNPS do not occur in high frequencies.
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False they occur with high frequency
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Describe a SNPS.
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Single base change in a DNA sequence hat occurs in a significant proportion (more than 1%) of a large population
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Where do most SNPs most commonly occur?
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in noncoding regions
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Remaining SNPs occur in ___ region and may alter the protein made by that coding region which could effect ___.
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coding; health
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What are some examples of SNPS that cause normal variation?
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eye color and height
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What might occur if an individual has a SNP in any protein involved in transport, absorption and or metabolism of a drug?
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They may alter the time the body is exposed to active forms of a drug or toxic byproducts
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Which liver protein has been linked to abnormal drug metabolism?
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CYP2C9
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As many as 40% of persons carry a SNP that produces a deficient ___protein, impairing metabolism in 1 in __medications
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CYP2C9; 5
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What is pharmacogenomics?
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examines how your genetic makeup affects your response to drugs
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ToF: many drugs that treat cancer are not fully active in the form in which they are give
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True: prodrugs
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How are drugs activated?
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By enzymes
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What happens if a person metabolizes a drug slowly?
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then the body doesnt make enough of the active form of the drug, and the standard doses of treatment may not work as well
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What can occur if a person has less efficient enzymes that deactivate drugs?
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then high levels of the unconverted drug remain in the body for a long time, increasing the drug's side effects
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What is tiopurine methyltransferase?
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an enzyme responsible for the metabolism of 6-mercaptopurine: a purine metabolite
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Genetic variations in the enzyme __ are found in about 10% of children
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TPMT
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Children with ___ should be tested for the enzyme TPMT.
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ALL
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To avoid severe side effects children with ALL with lower levels of __ are treated with lower doses of drugs?
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TPMT
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What type of cancers can be treated with fluorouracil (5-FU, Adrucil)?
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colorectal, breast, stomach and pancreatic
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What is the name of the enzyme that helps metabolize the drug fluorouracil?
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dihydropyrimidine dehydrogenase DPD
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What test is done on cancer patients going to receive fluorouracil?
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DPYD for the gene that limits the enzymes ability to function
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Information encoded in the DNA of the genome is coped by ___ and then carried to ribosomes where the instruction are used to assemble ___
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mRNA; proteins
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What occurs behind the scene of protein production from DNA--> mRNA --> protein?
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snippets called micro RNA
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What is the function of microRNA?
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binds to a genes mRNA and can prevent the instructions from reaching their target silencing the gene, and may modulate it in other ways
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What are micro RNAs?
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regulatory, non-coding RNAs, that might be involved in tumor formation
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What is the name of the micro RNA that may be and oncogene involved in B-cell lymphoma?
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mir-17-92
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What is the known cluster of microRNA found on chromosome 13 and found to be linked to many human cancers?
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c-Myc: transcription factor
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Who is Gregor Mendel?
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-Augustinian monk who cross-bred pea plants with different characteristics
-his observations led to laws regarding transmission of hereditary characteristics |
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What is meant by dominant?
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only one allele of a gene necessary to express that trait
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What does recessive mean?
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both alleles of a gene must be identical to express the trait
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What is heterozygous?
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alleles of a particular gene are non-identical
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what is homozygous?
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alleles of a particular gene are identical
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WHat are X linked traits?
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Traits that are passed from parents to offspring on the X chromosome
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What are the common X linked recessive traits?
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colorblindness and hemophilia
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The genes needed to distinguish red from __ are on the __ chromosome.
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green; X
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Is colorblind X link dominant or recessive?
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Recessive: usually only shows up in males
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What is the symbolic representation of family members taken from the family history?
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Pedigree
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How many generations are typically included in a pedigree?
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3
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ToF: there is a nomenclature for pedigrees
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True: developed by the Pedigree standardization task force of the national society of genetic counselors.
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Who are considered first degree relatives?
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parents, siblings and children
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Who are second degree relatives?
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half siblings, aunts, uncles, grandparents, nieces and nephews
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Third degree relatives are __ __
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first cousins
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What information must be acquired during the family history?
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-age, DOB, or year of birth
-relevant health info -diagnosis, age at diagnosis -age at death or years of birth/death -cause of death -ethnic background for each biological grandparent |
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What are the indications for genetic assessment in relation to cancer?
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-a cluster of the same cancer in close relatives
-cancer occuring at a younger age than expected in the general pop -more than one primary cancer in one person -evidence of autosomal dominant inheritance -bilateral cancer in any paired organ -cancers in an organ that are multifocal |
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In the genetic testing process, the consultation occurs with a ___
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qualified health professional with expertise in genetics
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What must the patient be informed about in terms of the genetic testing?
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Risk, benefit and limitations
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ToF: consent is needed for genetic testing
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TRUE
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How long does the blood work of genetic testing take to get results?
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3-4 weeks
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What are the risks of genetic testing?
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-loss of privacy
-psychosocial stress -confidentiality issue when health care provider dictates notes or records copied -genetic record contain info on family members - genetic information nondiscrimination act 2008 |
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ToF: in order to have hereditary breast and ovarian cancer syndrome, you must have a family hx of both breast and ovarian cancer?
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true
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what is the age of onset with HBOC syndrome?
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Early, under 50
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What is the required inheritance pattern to have HBOC syndrome?
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autosomal dominant through either mother or fathers side
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In order to have HBOC syndrome, the patient must have an increased incidence of tumors of other specific organs such as...
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prostate, mealnoma and pancreas
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What are the misc factors to HBOC syndrome?
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hx of male breast cancer
ASHKANAZI JEWISH ancestry |
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What is the cumulative risk of ovarian cancer by age 70 with a BRCA1 gene? with BRCA 2? what is the avg age of diagnosis for both?
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1. 40-50% age 52
2. 10-25% age 62 |
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ToF: the overall risk of carriers of BRCA 1 and 2 to develop ovarian cancer before 30 is high
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False; very low
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Other than ovarian cancer, what other reproductive problem are patients with BRCA 1 and 2 at higher risk for?
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fallopian tube and primary peritoneal cancer
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For women with HBOC, when should they have clinical breast exam?
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every 6-12 months beginning at age 25 or individualized based on earliest age of onset in the family
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At what age do women with BRCA1/2 have annual mammogram or MRI?
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25 or individualized
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When is a women with BRCA 1/2 recommended to have a salpingo-oopherectomy?
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between 35 and 40 and upon completion of childbearing or individualized
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what must occur if a women with BRCA 1/2 opts out of having a salpingo-oopherectomy>
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-TVU and CA 125 every 6 months beginning at 30 or 5-10 years prior to earliest onset in family member
-consider chemoprevention -discuss risk reducing mastectomy |
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What is the recommended protocol for men with genetic Hereditary breast and Ovarian cancer?
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-BSE training and education starting at age 35
-Clinical breast exam every 6-12 months starting at 35 -Consider baseline mammogram at age 40 annual if gynecomastia -adhere to screening guidelines for prostate ca |
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What is the most common of the inherited colon cancer susceptibility syndromes?
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Lynch syndrome
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What is the transmission of Lynch Syndrome
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autosomal dominant caused by germline mutation in one of the several DNA mismatch MMR genes,
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The 4 genes affected in Lynch syndrome are...
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MLH1
MSH2 MSH6 PMS2 |
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Lynch syndrome accounts for __ to __% of all colon cancer cases and is responsible for 2% of ___ cancers
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2 to 3; endometrial
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What is the general name for the cancer caused by Lynch Syndrome
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Hereditary Nonpolyposis colorectal cancer (HNPCC)
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What is the mean age of initial colorectal cancer with HNPCC?
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45
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People with HNPCC have an increased risk of what disorders?
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-Ovarian
-Upper urologic tract -Gastric -Small bowel -biliary/pancreatic -Brain Cancers |
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The lifetime risk of developing colon cancer is __ to __ % with individuals effected with HPNCC and 20-60% risk of endometrial
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Lynch syndrome
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How many relatives must be an individual have with HNPCC associated cancer to be considered to screen?
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3.
One should be a first degree relative of the other 2 and at least 2 successive generations should be affected. -one diagnosed before age 50 |
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What are the screening recommendations in terms of colon cancer for people with HNPCC?
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colonoscopy at age 20-25 or 2-5 years prior to the youngest age at diagnosis in the family, whichever comes first, repeat every 1-2 years
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ToF: people with HNPCC must have screening for pancreatic cancer early?>
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False: no recommendations
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ToF: a prophylactic hysterectomy is not a preferred treatment for HPNCC after child bearing years?
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FALSE: it is recommended
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What is FAP?
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Characterized by multiple (>100) adenomatous polyps in the colon and rectum developing after the first decade of life
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What % of all colorectal cancers are associated with FAP?
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1%
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where does the mutation occur in FAP?
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APC gene on chromosome 5q21
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Other than colon cancer, what are FAP patients also at risk for?
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-Duodenal cancer
-Childhood hepatoblastoma -gastric carcinoma -thyroid cancer -CNS tumors (mostly medulloblastomas) |
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When do you thyroid exams begin in children with FAP?
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in late teens
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At what age do children with FAP begin screening with sigmoidoscopies and colonoscopies?
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age 10 every 12 months
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What is the screening protocol for family members of children with HNPCC?
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Flex sig and colonoscopy every 12 months until age 24, every 2y until 34, every 3y until 44 then every 3-5 years thereafter.
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__ is raised in 2/3 of patients with hepatoblastoma
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AFP
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CHildren with FAP are recommended to have serum AFP testing and __ __ every 3-6 months until age 6 to check for hepatoblastoma.
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abdominal palpation
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Children with AFP often have a colectomy with __ __
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ileorectal anastomosis
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What is a restorative proctocolectomy and what does it require?
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ileal pouch anal anastamosis and requiers a temporary ileostomy
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What is the preferred form of chemoprevention for FAP?
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NSAIDs to prevent polyp burden
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What is the genetic makeup of Li-Fraumeni syndrome?
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germ-line mutation in the tumor suppressor gene p53
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What is Li-Fraumeni syndrome?
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characterized by the development of multiple tumors including soft tissue sarcomas, osteosarcomas, leukemia, brain tumors, adenocortical malignancies, and early onset breast cancer
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50% of carriers of LiFraumeni syndrome develop some form of cancer by age __; 90% do so by age ___
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30; 70
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__ families worldwide have li-fraumeni syndrome.
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400
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The most common intraocular malignancy of childhood is __ and exists in sporadic and __ form
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retinoblastoma; heritable
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What causes retinoblastoma?
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mutational inactivation of both alleles of the retinoblastom (RB1) gene, which maps to chromosome 13q14
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The majority of cases of retinoblastoma are in children under __ and 95% before age --
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2; 5
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What are the most common presenting signs of retinoblastoma?
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leukocoria and strabismus
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When can a dx for retinoblastoma be made?
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usually during a dilated indirect opth exam that is performed under anesthesia, the characteristic finding is a chalky, white gray retinal mass with soft friable consistency.
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the overall 5 year survival rate for children with retinoblastoma in US is > __%
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90
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How many years must pass for a child to be said to be cured from retinoblastoma?
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5
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ToF: patients with heritable retinoblastoma must be monitored for second malignancies throughout their lives.
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True
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what are secondary cancers associated with retinoblastoma?
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-melanomas
-osteogenic sarcoma -soft tissue sarcoma |
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The risk of second malignancy in children with retinoblastoma is __ __ af 50 years after original treatment
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35-40
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What are the names of the hereditary cancer syndrome cancers
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-von hippel-lindau
-multiple endocrine neoplasias -cowden syndrome -neurtofibromatosis |
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List the implications for NP in cancer?
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-ID at risk population
-Basic cancer risk assessment -Referrals for hereditary cancer eval -implement cancer prevention and detection -managing psychosocial ramifications of testing |
