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Genetics
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The study of genes and their role in inheritance. - Determines the way certain traits or conditions are passed down from one generation to another
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Genomics
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The study of all of a person's genes (the genome). - Interactions of genes with each other and with persons environment. - Study of complex diseases caused by genetic and environmental factors: heart disease, asthma, diabetes mellitus, and cancer.
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Genes
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The basic unit of heredity information located on a specific part of a chromosome. - They encode, or carry instructions for proteins that direct activities of cells and functions of the body. - Control cellular function, how quickly it grows, how often it divides, and how long it lives.
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Allele
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An alternative form of a gene occupying a pair of chromosomes, one coming from the mother and one coming from the father. - Each _______ codes for a specific inherited characteristic such as, eye color, hair texture, and blood type.
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Dominant Allele
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The trait or gene that is fully expressed in the phenotype of an individual.
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Recessive Allele
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The trait or allele that lacks ability to express itself.
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Autosome
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Any chromosome that is not sex chromosome. - Humans have 22 pairs
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Carrier
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Individual who carries a copy of a mutated gene for a recessive disorder.
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Chromosome
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A compact structure containing DNA and proteins present in nearly all cells of the body. - Normally each cell has 46 _______ in 23 pairs. - Each biological parent contributes one of each pair of ________.
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Codominance
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Two dominant versions of a trait that are both expressed in the same individual.
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Congenital disorder
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Condition present at birth
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Familial Disorder
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Condition that affects more than one person in a family.
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Genetic Risk Factor
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A change in a gene that increases a person's risk of developing a disease.
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Genome-wide association study (GWAS)
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A study approach that involves scanning complete set of DNA (genomes) of many individuals to find genetic variations associated with a particular disease.
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Genotype
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Genetic identity of an individual. This identity does not show as outward characteristics. - Genetic Makeup
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Hereditary
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Transmission of a disease, condition, or trait from parent to children.
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Heterozygous
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Having two different alleles for one given gene, one in hearted from each parent.
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Homozygous
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Having two identical alleles for one given gene, one inherited from each parent.
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Locus
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Position of a gene on a chromosome.
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Mutation
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A change in DNA or a gene. - Sometimes these changes are passed from parent to children.
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Oncogene
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Gene that is able to initiate and contribute to the conversion of normal cells to cancer cells.
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Pedigree
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Family tree that contains the genetic characteristics and disorders of that particular family.
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Pharmacogenetics
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Study of variability of responses to drugs related to variations in single genes.
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Pharmacogenomics
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Study of variability of responses to drugs related to variations in and interactions of multiple genes
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Phenotype
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Observable traits or characteristics of an individual - Hair color - Eye color
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Protooncogene
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Normal cellular genes that are important regulators of normal cellular processes. - Mutations can activate them to become oncogenes.
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Trait
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Physical characteristic that one inherits, such as hair or eye color.
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X-linked gene
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Gene located on the X chromosome. - Sex-linked disorders are only seen in males.
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Deoxyribonucleic acid (DNA)
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Nucleic acid that makes up genes. - Stores genetic information - Encodes instructions for specific protein synthesis needed to maintain life.
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Nitrogenous Bases
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Adenine (A); Guanine (G); Cytosine (C); Thymine (T)
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DNA Base Pairs
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Adenine (A) paired with Thymine (T); Cytosine (C) paired with Guanine (G)
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Nucleotides
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Attached base pair, sugar molecule, and phosphate molecule.
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Double Helix
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Nucleotides are arranged in two long strands that twist to form a spiral shape.
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Ribonucleic Acid
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Contains the nitrogenous bases adenine (A); Guanine (G); Cytosine (C); Uracil (U) - Single strand and contains ribose sugar
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Protein Synthesis
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The making of proteins
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Protein Synthesis - Transcription
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The process by which messenger RNA (mRNA) is synthesized from single-stranded DNA.
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Protein Synthesis - Translation
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The mRNA becomes attached to a ribosome and this process begins. - Transfer RNA (tRNA) arranges the amino acids in the correct sequence.
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Mitosis
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A type of cell division that results in the formation of genetically identical daughter cells. - Before cell devision, chromosomes duplicated, daughter cells receive exact replica of chromosome from original parent cell.
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Meiosis
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Occurs only in sexual reproductive cells - Number of chromosomes are reduces, resulting in half the chromosomes. - Oocytes and Sperm contain only a single copy of each chromosome.
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Mutations
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Any change in the usual DNA sequence.Subtle variations in DNA (Many forms)- Polymorphisms. - Slight variations among people such as hair and eye color. - Some gene variations may result in disease or increased risk for disease
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Germline Mutations
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Inherited from a parent, passed on from parent to child. - Present in oocyte and sperm cells. - Present throughout a person's life, virtually in every cell.
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(Acquired (somatic) Mutations
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Occur in the DNA of a cell at some time during a person's life. - Passed on to all cells that develop from a single cell. - Cannot be passed on to the next generation - Occur if: 1) a mistake is made as DNA replicates during cell division 2) environmental factors alter the DNA
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Environmental Factors causing Mutations
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DNA damage occurs from: - Ultraviolet (UV) radiation- leading to skin cancer - Toxins in cigarettes- lead to lung cancer - Chemotherapy drugs to treat cancer- damages cancer cells and healthy cells, increasing the persons risk of developing secondary cancers.
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Autosomal Dominant Disorders
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Caused by a mutation of a single gene pair (heterozygous) on a chromosome.
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Autosomal Dominant Disorders - Variable Expression
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Symptoms expressed by the individuals with the mutated gene vary from person to person even though they have the same mutated gene.
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Autosomal Dominant Disorders - Incomplete penetrance
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High probability of occurring in families, sometimes these disorders cause a new mutation or skip a generation
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Autosomal Recessive Disorders
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Caused by mutations of two gene pairs (homozygous) on a chromosome. - A person who inherits one copy of the recessive allele does not develop the disease because the normal allele predominates- this person is a carrier.
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X-linked Recessive Disorders
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Caused by a mutation on the X chromosome, - Usually only men are affected by this disorder b/c women who carry the mutated gene have another x chromosome to compensate for the mutation. - Can be transmitted to their offspring
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Multifactorial Inherited Conditions
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Caused by a combination of genetic and environmental factors. - These disorders run in families, but does not show the same inherited characteristics as the single gene mutation condition. - Ex: diabetes mellitus, obesity, hypertension, cancer, and coronary artery disease
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Human Genome Project (HGP)
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Completed in 2003, mapped the entire _____ ______. - Knowledge gained will... 1) help improve the diagnosis of disease 2) allow for earlier detection of genetic predisposition to disease 3) play a critical role in determining risk assessment for genetic-related diseases 4) assist in matching organ donors with transplant recipients.
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Genetic Disorder
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Caused in whole or in part by an alteration in the DNA sequence - Can be inherited (person born with altered genetic code) - Can be acquired (replication errors, damage to DNA from toxins) - Caused by: 1) mutation in one gene (single gene disorder) 2) mutations in multiple genes (multifactorial inheritance disorder) 3) damage to chromosomes (changes in the number or structure of entire chromosome)
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Single Genetic Disorder
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Examples: - Cystic fibrosis - Sickle cell disease - Polycystic kidney disease Pattern of inheritance: - autosomal dominant - autosomal recessive - X-linked Relatively rare disorders
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Multifactorial Genetic Disorders
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Complex diseases resulting from small inherited variation in genes, often acting with environmental factors. Examples: - Heart disease - Diabetes - Most cancers Some diseases can be caused by rare hereditary mutations in single genes. Genetic mutations that cause or predispose person to the diseases run in families. Example: - Breast Cancer - Inheritance of mutated BRCA1 or BRCA2 gene, significant risk of developing the disease.
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Epigenetics
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The study of changes in gene function that do not involve a change in DNA sequence. - Focus: * How and when particular genes are expressed * Environment factors affects expression of the gene positively and negatively * Changes can be inherited - Identical twins do not have the same genetic makeup, they don't always develop the same diseases at the same rate.
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Chromosome Disorders
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Caused by structural changes within chromosomes or by an excess or deficiency of the genes located on chromosomes. Examples: - Down Syndrome: extra copy of chromosome 21 (called trisomy 21) * No abnormal gene, but 3 copies of chromosome 21 - Chronic myelocytic leukemia: caused by chromosomal translocation in which portions of chromosomes 9 and 22 are exchanged (translocation called Philadelphia Chromosome)
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Genetic Testing
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Any procedure done to analyze chromosomes, genes, or any gene product that can determine whether a mutation or predisposition to a condition exists. - Samples of blood, skin, hair, or saliva can be used - Tissues and cells can be obtained prenatally - Results are used to diagnose illness or risk for disorder, and provide basis for appropriate treatment.
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Genetic Information Nondiscrimination Act (GINA)
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Genetic testing results in medical records may not be kept private. - GINA protects people from discrimination by employers and health insurance companies.
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Diagnostic Testing
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- Used to diagnose, rule out, confirm a specific genetic or chromosomal condition - Used to confirm findings when signs and symptoms suggest genetic disorder - Can be preformed at any time during life, not available for all genes or genetic conditions - Examples: * Cystic Fibrosis * Sickle cell disease * Polycystic kidney disease * Hemophilia * Familial hypercholesterolemia
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Carrier Screening
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- Can be used to identify unaffected individuals who carry one copy of a gene - Offered to individuals who have family history of genetic disorders, ethnic groups, increased risk of specific genetic conditions - Both parents tested, provide information about couple's risk of having a child with genetic condition. - Examples: * Cystic Fibrosis * Sickle cell disease * Hemophilia
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Preimplantation Genetic Diagnosis (PGD)
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- Fertilized embryos tested before implantation and pregnancy - Allows embryos free of particular disorders to be placed into uterus - Embryos that test positive for genetic disorders can be destroyed. - Examples: * Individuals known to have or be carrier for a genetic mutation (Huntington's disease)
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Prenatal Diagnostic Testing
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- Fluid obtained from amniocentesis or tissue from chorionic villus used to obtain fetal cells - Used to detect changes in genes or chromosomes of fetus before birth - Type of testing offered to couples with increased risk of having a baby with genetic or chromosomal disorder - Can decrease couple's uncertainty or help them decide whether to terminate the pregnancy. - Examples: * Down Syndrome * Other genetic alterations in fetuses
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Newborn Screening
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- Most widespread use of genetic testing - Early intervention to treat these disorders can eliminate or reduce symptoms that might otherwise cause a lifetime of disability - Examples: * Phenylketonuria * Congenital hypothyroidism * Cystic Fibrosis
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Presymptomatic Testing
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- Used to detect genetic mutations associated with disorders that appear later in life - Can be helpful to people who have a family member with a genetic disorder, but no features of disorder themselves at time of testing - Results can provide information about a person's risk of developing specific disorder and help with decisions about treatment. - Examples: * Huntington's disease * Adult polycystic kidney disease * Hemochromatosis * Familial adenomatous polyposis * Hereditary nonpolyposis colorectal cancer syndrome
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Predictive Testing
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- Can identify mutations that increase a person's risk of developing disorders - If results are positive, person can have prophylactic measures (Ex: mastectomy, oophorectomy) to prevent development of cancer - Examples: * Breast Cancer * Ovarian Cancer
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Forensic Testing
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- Done to identify an individual for legal purposes - Examples: * Identify crime of victims in catastrophic situations * Rule out or implicate a crime suspect
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Parental Testing
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- Establish biological relationships between people - Example: * Paternity testing
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Pharmacogenetic Testing
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- Identifies genetic variations that influence a person's response to drugs - Results provide information to help select drug therapy that is best for the person. - Example: * Warfarin (Coumadin) dose
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Positive Genetic Test
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The laboratory found a change in a particular gene, chromosome, or protein that was being tested - Results may confirm diagnosis (Huntington's Disease) - Indicate a person is a carrier of a particular genetic mutation (Cystic Fibrosis) - Identify an increased risk of developing a disease (breast cancer) - Suggest need for further testing
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Negative Genetic Test
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The laboratory did not find an altered form of the gene, chromosome, or protein under consideration. - Results cain indicate a person is not affected by a particular disorder - Not a carrier of a specific gene mutation - Does not have an increased risk of developing a certain disease.
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Direct-to-consumer genetic test (at-home testing)
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- Marketed directly to consumers via television, print advertisements, or internet. - Test kit is mailed to persons home - Collecting DNA sample by swabbing the inside of the cheek, and mailing sample back to laboratory. - Consumers are notified of their results by mail, via telephone, or posted online. - Some cases, genetic counselor or health care provider is available to explain results.
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DNA Finger Printing
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Extracting DNA from cells in a sample of blood, saliva, semen, or appropriate fluid or tissue.
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Polymerase chain reaction (PCR)
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- Key element in genetic finger printing - Essential technique in finding mutations in genes, quick and easy method to providing unlimited copies of DNA to RNA sequence in a small sample. - Used extensively in forensic medicine to identify criminal suspects from blood, hair, saliva, and semen. - Used in finding evidence to free innocent prisoners and in paternity testing - Used as a confirmatory test in HIV testing. * Example: Infant of a mother who is HIV-antibody positive and tests HIV positive
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DNA Microarray (DNA chip)
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This technology is used to measure the expression levels of large numbers of genes simultaneously or to genotype multiple regions of a genome. - Chips are laid out by robots and position DNA fragments - Fluorescent-tagged molecules are washed over the DNA fragments - Some molecules (W/ green fluorescent tags) bind to their complimentary sequence - These molecules are identified b/c they glow under fluorescent light when scanned with automated equipment. Studying which genes are active and inactive in different cell types help to understand: 1) how these cells function normally 2) how they are affected when various genes do not perform properly.
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Gene Therapy
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Experimental Technique that uses genes to treat of prevent disease - Approaches: * Replacing a mutated gene with a healthy copy of the gene * Inactivation, or "knocking out," a mutated gene that in functioning improperly * Introducing a new gene into the body to help fight a disease
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Stem Cell Therapy
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May allow for the regeneration of lost tissue and restoration of function in various diseases _____ _____ are unspecialized cells in the body that have the ability to... 1) remain in their unspecialized state and divide 2) differentiate and develop into specialized cells such as brain or muscle
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Embryonic Stem Cells
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Come from the embryo at a very early stage in development (4 to 5 days), have the ability to become any one of the hundreds of types if cells in the human body.
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Adult (somatic) Stem Cells
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Undifferentiated cells that are found in small mungers in many adult organs and tissues, including brain, bone marrow, peripheral blood, blood vessels, skeletal muscle, skin, teeth, heart, GI tract, liver, ovarian epithelium, and testes. - The undifferentiated cells taken from a specific region, may only develop into that specific cell (Ex: stem cells from liver, may only develop into liver cells)
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Punnett Squares - If the mother and father are both carriers for cystic fibrosis
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There is a 25% chance that the offspring will have cystic fibrosis
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Punnett Square - If the mother is a carrier for the hemophilia gene and the father has a normal genotype
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There is a 50% chance that any male offspring with have hemophilia There is a 50% chance that any female offspring will be a carrier
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Punnett Square - If the mother has a normal genotype and the father has Huntington's Disease
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There is a 50% chance that the offspring will have the disease
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Nursing Management - Genetics and Genomics
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- With a clear understanding, you can assist the patient and family in making critical decisions related to genetic issues (genetic testing). - Collaborate with genetic nurse to genetic counselor - Be an advocate for patients and families by facilitation access to genetics resources * Tailored to patient based on culture, religion, knowledge level, literacy, and preferred language - Identify and assess inheritance patterns and explain them to the patient and family through the use of family pedigrees and Punnett Squares - Maintain patients confidentiality and respect the patient's values and beliefs b/c genetic information may have major health and social implications
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Nursing Assessment Family History
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- Key features of a family history may increase a person's risk for genetic-related diseases are... * Disease in more than one close relative * Disease that does not usually affect a certain gender (breast cancer in males) * Diseases that occur at an earlier age than expected (MI before age 35) * Certain combinations of disease within a family (Ex: breast and ovarian cancer, heart disease, and diabetes)
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NCLEX 1) If a person is heterozygous for a given gene, it means that the person a. is a carrier for a genetic disorder b. is affected by the genetic disorder c. has two identical alleles for the gene d. has two different alleles for the gene
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d. Has two different alleles for the gene
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NCLEX 2) Common causes of genetic mutations include (select all that apply) a. DNA damage from toxins b. DNA damage from UV radiation c. inheritance of altered genes from father d. inheritance of altered genes from mother e. inheritance of somatic mutations from either parent
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a. DNA damage from toxins b. DNA damage from UV radiation c. inheritance of altered genes from father d. inheritance of altered genes from mother
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NCLEX 3) A father who has an X-linked recessive disorder and a wife with normal genotype will a. pass the carrier state to his male children b. pass the carrier state tot all of his children c. pass the carrier state to his female children d. not pass on the genetic mutation to any os his children
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c. pass the carrier state to his female children
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NCLEX 4) What characterizes multifactorial genetic disorders? a. Genetic testing available for most disorders b. Commonly caused by single gene alterations c. Many family members report having the disorder d. Caused by complex interactions of genetic and environmental factors
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d. Caused by complex interactions of genetic and environmental factors
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NCLEX 5) If a person tests positive for a genetic mutation, it means (select all that apply) a. that the laboratory found an alteration in a gene b. that the person is predisposed to develop a genetic disease c. that the person will develop the disease at some point d. there is the possibility that other family members may also be at risk e. that the person should not have any children or any additional children
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a. that the laboratory found an alteration in a gene d. there is the possibility that other family members may also be at risk
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NCLEX 6) What role does pharmacogenetics have in health care? a. It can assess individual variability to many drugs b. It can be used to determine the effectiveness of a drug. c. it provides important assessment data for gene therapy d. It can assess the variability of a drug responses due to single genes
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d. It can assess the variability of a drug responses due to single genes
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NCLEX 7) A couple who recently had a son with hemophilia A in consulting with a nurse. They want to know if their next child will have hemophilia A. The nurse can tell the parents that if their child is a a. boy, he will have hemophilia A b. boy, he will be a carrier of hemophilia A c. girl, she will be a carrier of hemophilia A d. girl, there is a 50% chance she will be a carrier of hemophilia A
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d. girl, there is a 50% chance she will be a carrier of hemophilia A
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