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Advanced Patho Exam 2 > Exam 2: Genetics > Flashcards

Exam 2: Genetics Flashcards

1
Q

what is Mendelian Inheritance

A

refers to an inheritance pattern that follows the law of segregation and independent assortment, in which a gene inherited from either parent segregates into gametes at an equal frequency

Certain patterns of how traits are passed from parents to offspring

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2
Q

what is law of segregation?

A
  • states that for any trait, each parent pairing of genes split and one gene passes from each parent to an offspring
    -which particular gene in a pair gets passed on is completely up to chance

only one of the two gene copies present in an organism is distributed to each gamete (egg or sperm cell) that it makes, and the allocation of the gene copies is random.

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3
Q

what is law of Independent Assortment?

A

-states that different pairs of alleles are passed onto the offspring independently of each other, therefore, inheritance of genes at one location in a genome does not influence the inheritance of genes at another location

the alleles of two (or more) different genes get sorted into gametes independently of one another. In other words, the allele a gamete receives for one gene does not influence the allele received for another gene.

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4
Q

what are the three major patterns of Mendelian Inheritance?

A
  • autosomal dominant
    -autosomal recessive
    -X-linked
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5
Q

what does Mendelian inheritance patterns refer to?

A

to observable traits, not to genes

Some alleles at a specific locus may encode a trait that segregates in a dominant manner, whereas another allele may encode the same or a similar trait, but instead it segregates in a recessive manner

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6
Q

what is autosomal dominant?

A

o describes a trait or disorder in which the phenotype is expressed in those who have inherited only one copy of a particular gene mutation (also known as, heterozygotes)
o specifically refers to a gene on one of the 22 pairs of autosomes (any chromosome that is not a sex chromosome)

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7
Q

Probability of transmitting an autosomal dominant gene mutation to offspring:

A
  • each offspring has a 50% chance of inheriting the mutation
    -Gender does not matter, all affected equally
    -mother/father are equally likely to transmit or inherit the disorder
    -offspring of an affected parent are equally likely to inherit or transmit the disorder
    -Phenotype expressed with one copy of abnormal gene
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8
Q

what is autosomal recessive?

A

o describes a trait or disorder requiring the presence of two copies of a gene mutation at a particular locus in order to express observable phenotype;
o specifically refers to genes on one of the 22 pairs of autosomes (non-sex chromosomes)
 need 2 copies of the gene mutation for the offspring to exhibit the phenotype of the mutation

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9
Q

what generation is autosomal dominant seen in?

A

often seen in multiple generations

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10
Q

what generation is autosomal recessive seen in?

A

usually seen in a single generation of a family

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11
Q

what gender is most likely to transmit or inherit autosomal dominant?

A

mother/father are equally likely to transmit or inherit the disorder

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12
Q

what gender is most likely to transmit or inherit autosomal recessive?

A

men and women are equally likely to transmit and inherit this disorder

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13
Q

Probability of transmitting an autosomal recessive gene mutation to offspring

A
  • each offspring in a family with autosomal recessive disorder, where both parents have the autosomal recessive gene, each offspring of that generation has a 25% chance of inheriting the mutation
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14
Q

what is X-linked Dominant?

A

o describes a dominant trait or disorder caused by a mutation in a gene on the X chromosome. The phenotype is expressed in heterozygous females as well as hemizygous males (having only one X chromosome)
o affected males tend to have a more severe phenotype than affected females
 rare, the offspring most of the time doesn’t survive

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15
Q

in a situation, where both parents are autosomal recessive carriers but are not affected, what are the chances of having an affected offspring?

A

25%
-sex of offspring does not matter

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16
Q

Transmission of an X linked dominant gene mutation from an affected female to her offspring is similar to autosomal dominant inheritance;

A
  • each child regardless of gender has a 50% chance of inheriting the mutation
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17
Q

Transmission of an X-linked dominant gene mutation form and affected male to his offspring is similar to X-linked recessive inheritance

A

all of his daughters and none of his sons will inherit the mutation

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18
Q

what is X-linked Recessive

A

a way a genetic trait or condition can be passed down from parent to child through mutations (changes) in a gene on the X chromosome.

o a mode of inheritance in which a mutation in a gene of the X chromosome causes the phenotype to be expressed in males who are hemizygous for the gene mutation
 (i.e. they have only one X chromosome)
o and in females who are homozygous for the gene mutation
 (i.e. they have a copy of the gene mutation on each of their two X chromosomes)
o Carrier females who only have one copy of the mutation do not usually express the phenotype although differences in X-chromosome inactivation can lead to varying degrees of clinical expression in carrier females
 Affected males are always related to each other through females
 Male to male transmission does not occur!!
o The disorder will only be on males!!
o Seen more vs x-linked dominant

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19
Q

CALCULATE THE PROBABILITY OF PASSING ON A GENETIC DISORDER TO AN OFFSPRING GIVEN THE TYPE OF INHERITANCE: Autosomal dominant

A

each kid has 50% chance

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20
Q

CALCULATE THE PROBABILITY OF PASSING ON A GENETIC DISORDER TO AN OFFSPRING GIVEN THE TYPE OF INHERITANCE: Autosomal Recessive

A

each kid has 25%

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21
Q

CALCULATE THE PROBABILITY OF PASSING ON A GENETIC DISORDER TO AN OFFSPRING GIVEN THE TYPE OF INHERITANCE: X-linked dominant

A

each kid has 50% chance

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22
Q

CALCULATE THE PROBABILITY OF PASSING ON A GENETIC DISORDER TO AN OFFSPRING GIVEN THE TYPE OF INHERITANCE: X-linked recessive

A

depends on what parents have and if mom has disease or is carrier

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23
Q

Define heterozygote advantage

A
  • Heterozygotes: 2 alleles are non-identical at the locus
  • alleles with observable effects=dominant
    -alleles with hidden effects = recessive
    -heterozygous geno/phenotype has a higher evolutionary fitness (able to survive and reproduce) than either homozygous geno/phenotype
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24
Q

what are examples of heterozygotes advantages?

A
  • Tay Sachs heterozygotes advantage–> increase resistance to TB, Jewish population use to live in densely populated areas
    -Sickle Cell anemia–> protection against malaria, ppl with the mutation arent less likely to get bitten by the mosquitoes that transmit the diease but they are less likely to get sick or die as a result.
    **carriers are less susceptible to malaria because they make some sickled RBCs, but they make enough RBCs that they arent negatively affected by sickle cell anemia
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25
Q

what is the definition of pentrance?

A

the % of individuals that have a mutation of a disorder, that they will actually exhibit the “phenotype” clinical symptoms of that disorder

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26
Q

what is complete penetrance?

A

symptoms are present in all individuals who have the disease-causing mutation 100%

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27
Q

what is incomplete penetrance?

A

symptoms are not present in all individuals who have the disease-causing mutation <100%

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28
Q

IDENTIFY DISORDERS/DISEASES WITH A STRONG FAMILIAL HISTORY: Huntington’s

A

Inherited in an autosomal dominant manner with 100% penetrance

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29
Q

IDENTIFY DISORDERS/DISEASES WITH A STRONG FAMILIAL HISTORY: BRCA1/2- Breast and Ovarian Cancer

A

Inherited in an autosomal dominant manner, with 60-85% penetrance

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30
Q

IDENTIFY DISORDERS/DISEASES WITH A STRONG FAMILIAL HISTORY: Colorectal Cancer

A

o Autosomal dominant
o Hereditary Nonpolyposis Colorectal Cancer (HNPCC)
 4 mismatched repair genes (MSH2, MLH1, MSH6, PMS2) have been identified
 Colonoscopy at an earlier age and more often
o Familial adenomatous polyposis (FAP)
 Inactivation of tumor suppressor gene, APC, on chromosome 5
 Fairly rare

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31
Q

IDENTIFY DISORDERS/DISEASES WITH A STRONG FAMILIAL HISTORY: Sickle cell

A

Autosomal recessive

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32
Q

IDENTIFY DISORDERS/DISEASES WITH A STRONG FAMILIAL HISTORY: Hereditary Hemochromatosis (HFE-HH)

A

o Autosomal recessive
o Penetrance for the p.Cys282Tyr (homozygotes) is relative high, but NOT 100%
o Penetrance for the p.Cys282Tyr and p.His63Asp (heterozygotes) is low, 0.5-2%

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33
Q

IDENTIFY DISORDERS/DISEASES WITH A STRONG FAMILIAL HISTORY: Alzheimer

A

o Familial (FAD) characterizes families that HAVE MORE THAN one member with AD, and usually implies multiple affected persons in more than one generation
o Early onset FAD, onset is consistently before age 60-65, often before age 55
 Approx. 60% of early-onset AD, is familial, with 13% appearing to be inherited in an autosomal dominant manner.

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34
Q

IDENTIFY DISORDERS/DISEASES WITH A STRONG FAMILIAL HISTORY: CAD

A

o Genetic susceptibility for CAD
 Early onset of CAD
* <55 for men
* <65 for women
 Involvement of multiple vessels for atherosclerosis
 Angiographic severity
 Two or more close relatives with CAD
o Female relatives with CAD
 Presence of related disorders such as diabetes in close relative
 Presence of multiple established/emerging risk factors in close family members
 Absence of established risk factors in family members with CAD such as smoking or hypertension

35
Q

IDENTIFY DISORDERS/DISEASES WITH A STRONG FAMILIAL HISTORY: hypertension

A

multiple genetic variants

36
Q

IDENTIFY DISORDERS/DISEASES WITH A STRONG FAMILIAL HISTORY: Diabetes

A

o Both type 1 and 2 are complex multifactorial diseases and this has made the search for a distinctive genetic component difficult and slow
o For T2D, at least 11 genetic variants have been found that are associated with the population of individuals with the disease. These along with a multitude of environmental factors result in a very complex picture of disease initiation, development and outcomes
o At least 10 genetic loci have been shown to have association with T1D

37
Q

IDENTIFY DISORDERS/DISEASES WITH A STRONG FAMILIAL HISTORY: Pulmonary conditions

A

o Asthma: studies to find genotype instead of waiting for phenotype for treatment
o COPD: small percentage have alph-1 antitrypsin

38
Q

IDENTIFY DISORDERS/DISEASES WITH A STRONG FAMILIAL HISTORY: Mental Illness

A

o Autism spectrum disorder
 If 1 twin has it 90% the other identical twin will
o Depression

39
Q

IDENTIFY MUTATIONS AND THEIR ASSOCIATED GENETIC DISORDERS: Huntington Disease

A

o autosomal dominant with 100% penetrance
o “severe neurologic disorder — progressive dementia, increasingly uncontrollable movements of the limbs, and psychiatric disturbances”
o mean age onset 33-44 years of age, average age of death 54-55 years.
 Mutation is an expansion of 36 or more CAG trinucleotide repeats in the HTT gene
* 36-39 repeats- “reduced penetrance”
o At risk for HD but may not develop symptoms
* >40 repeats- “full penetrance”
* More than 60 repeats will experience juvenile onset symptoms
 Normal- 26 or fewer CAG repeats
 Intermediate- 27-35 CAG repeats
* Is not at risk of developing symptoms, but because of instability in the CAG tract, may be at risk of having an offspring with the allele in the HD-causing range

40
Q

IDENTIFY MUTATIONS AND THEIR ASSOCIATED GENETIC DISORDERS: Breast and Ovarian Cancer (BRCA)

A

o autosomal dominant with 60-85% penetrance
 Mutations in BRCA 1 (chromosome 17) and BRCA 2 (chromosome 13) genes
 Both genes when functioning normally act as a tumor suppressor genes
o Overall prevalence is 1:400-1:800 but varies according to ethnicity
 Ashkenazi Jewish ancestry has the highest estimated
Prevalence → there is an Ashkenazi Jewish Panel that can be ordered
o Risk to Family Members
 all individuals with a mutation in BRCA1 or BRCA2 have inherited it from a parent.
 The parent may or may not have had a cancer diagnosis depending on the penetrance of the mutation, the gender of the parent with the mutation, the age of the parent with the mutation, and other variables.
 It is appropriate to offer genetic testing to both parents of an individual with a BRCA1 or BRCA2 mutation to determine which side of the family is at risk.
o Offspring of an individual with a BRCA1/2 mutation
 The offspring of an individual identified as having a BRCA1 or BRCA2 mutation have a 50% chance of inheriting the mutation!!!!!
 The risk of developing cancer, however, depends on numerous variables including the penetrance of the mutation and the gender and age of the individual.

41
Q

IDENTIFY MUTATIONS AND THEIR ASSOCIATED GENETIC DISORDERS: HFE associated hereditary hemochromatosis

A

o Hemochromatosis is a condition in which there is high absorption of iron from the intestinal mucosa
 Excessive storage of iron in liver, skin, pancreas, heart, joints, testes
* Liver cirrhosis is a major complication
o Individuals who are treated prior to the onset of cirrhosis have a normal lifespan
 Early symptoms- abdominal pain, weakness, lethargy, weight loss
* Symptoms usually occur between ages 40-60 years
o Diagnosed later on in adulthood
* Alcohol consumption worsen symptoms!!
 Men > women
o On chromosome 6 in autosomal recessive manner
 two mutations; p.Cys282Tyr and p.His63Asp
o initial test is Biochemical and not genetic!
 Transferrin-iron saturation (TS)
* measures the bloods capacity to bind to iron with transferrin (protein)
o Penetrance for homozygous (one of the mutations) is high (not 100%)
o Penetrance for heterozygous (both mutations) is low (0.5-2%)

42
Q

IDENTIFY MUTATIONS AND THEIR ASSOCIATED GENETIC DISORDERS: Alzheimer Disease

A

o Associated mutations on chromosome 21, 14, and 1 but just because someone has the mutation does not mean they will get the disease
o No genetic test for “normal” AD →
 AD beginning after 60 and not associated with an extensive family hx of AD
o APOE e4 allele. Not specific or sensitive for “asymptomatic” people
o Familial AD (FAD)
 characterizes families that have more than one member with AD and usually implies multiple affected persons in more than one generation.
* Basically, multiple people in a family that has it
o Early-onset FAD (EOFAD)
 onset is consistently before age 60 to 65 years and often before age 55 years.
* Approximately 60% of early-onset AD is familial, with 13% appearing to be inherited in an autosomal dominant manner
 Approximately 1%-6% of all Alzheimer disease (AD) is early onset (age <60-65 years)
o Early onset AD includes the designations of AD1, AD3, and AD4 (molecular genetic testing is available for these three genotypes)  you don’t need to know the designations!

43
Q

IDENTIFY MUTATIONS AND THEIR ASSOCIATED GENETIC DISORDERS: Colorectal cancers (CRC)

A

o Autosomal dominant
o Familial adenomatous polyposis (FAP)
 Something wrong with tumor suppressor gene on chromosome 5
 Rare
o Hereditary nonpolyposis colorectal cancer (HNPCC) “Lynch Syndrome”
 Increases risk for many types of cancers; colon, stomach, rectum
 4 mismatch repair genes
* MLH1, MSH2, MSH6, PMS2, EPCAM genes are involved in repairing errors that occur when DNA is copied in preparation for cell division
* Because these genes work together to fix DNA errors, it is why this is known as a mismatch repair gene
* Mutations in any of these genes prevent the proper repair of DNA replication errors
o As the abnormal cells continue to divide, the accumulated errors can lead to uncontrolled cell growth and possibly cancer
 More common
 Occasionally have noncancerous benign growths in the colon, polyps
o Individuals in families with multiple generations of members with CRC have the option of a genetic test to determine if they carry the family mutation

44
Q

what is the treatment for Huntington Disease?

A

o No treatment available, only symptom management
 Pharm- typical neuroleptics (Haldol), atypical (olanzapine), benzos, anti-parkinsonian agents, psychotropic drugs
* Attention to side effects of medications
 Supportive care- (nursing needs, eligibility for state and federal benefits)
 Surveillance- (eval for the severity of chorea, rigidity, gait problems, depression, behavioral changes, cognitive decline)
o Genetic testing for HD should never be offered outside of a referral to a genetic counselor!!!
 A LOT of counseling is needed! There is a protocol and there are steps
 Suicide rates are HIGH
 Disclosure of genetic test results to other family members may be a complex process for these individuals

45
Q

Symptoms of Huntington disease

A

o Symptoms- hallmark of hyperkinesia.
 Chorea begins in the face and arms, eventually affecting the whole body

46
Q

Management of Breast and Ovarian Cancer

A

 Start screening!
* Mammograms start least 10 years prior to the earliest onset of a family member
o If mom was diagnosed with breast cancer at 33, you will start getting mammograms at 23 years of age!
* Uterine US
* Annual breast MRI
* CA125 blood test
o Measures the amount of protein CA125- cancer antigen in the blood
o May be used to monitor certain cancers during and after treatment
 Remove ovaries by age 40 or when you are done having children → RISK DROPS BY 50% IN DEVELOPING BREAST CA
* CONS; Menopausal at a young age
 Prophylactic mastectomy, even on the unaffected breast

47
Q

what is the treatment for HFE associated hereditary hemochromastosis?

A

 Periotic phlebotomy is the recommended treatment
 Weekly, until ferritin levels are normal or low

48
Q

what is the screening for colorectal cancers?

A

 earlier and more frequent colonoscopies
* start at an earlier age (20-25 vs. 50) and more frequently (every 1-2 years vs. every 5-10 years)
* colonoscopy every 3 years in individuals at risk for HNPCC reduced the risk of developing CRC by 62% and prevented disease-related deaths

49
Q

how does the study of genomics affect healthcare?

A
  • common diseases and gemonics
    o Most human diseases result from the interaction between genetic factors and modifiable environmental factors such as chemical exposures, and behavioral factors like diet and lifestyle
  • The field of genomics studies a person’s complete set of genes and their functions, including interactions with environmental and behavioral factors
  • Potential for early identification of susceptible individuals
  • Development of targeted treatments that might prevent the disease or ameliorate the impact of the disease
    o Increase compliance of treatment, if there is “no side affects”
  • Genomics have not lived up to the hype of clinical possibilities
  • Adults may have a genetic test to determine risk for a future disease (pre-symptomatic genetic test) or diagnose symptoms
    o As a provider, remember the family is in reality being tested and so planning conversations for disclosure of test results is an important component of care
  • Genetic testing (especially for HD) should not be offered outside of a referral to a genetic counselor!!!
  • Allows for early treatment and prevention when available
  • In some cases, no treatment is available so then emotional support
  • Some patients may misinterpret results as with BRCA and result of DNA variant of uncertain clinical significance
    o Confusing result for individuals because you are telling them a mutation was detected but we don’t know what it means
  • Primary care will be required to integrate genomics into clinical medicine
  • Identifying genomics may provide new treatment strategies
50
Q

Benefits of prenatal testing

A

o Genetic tests can help to
 Diagnose your disease
 Pinpoint genetic factors that caused your disease
 Predict how severe your disease might be
 Choose the best medicine and correct dose
 Discover genetic factors that increase your disease risk
 Find genetic factors that could be passed to our children
 Screen newborns for certain treatable conditions
o Quad marker screen (15-20 week gestation)
 Down syndrome (Trisomy 21)
 Trisomy 18 (Edwards syndrome)
 Open neural tube defects

51
Q

what can newborn screening detect?

A

o Phenylketonuria (PKU)
 Protein assayed
 Autosomal recessive disorder caused by mutations in the PAH gene on chromosome 12
 Early treatment
o Congenital hypothyroidism
o Sickle Cell

52
Q

define: phenotype

A

the observable physical and/or biochemical characteristics of the expression of a gene; the clinical presentation of an individual with a. particular genotype

53
Q

define: penetrance

A

o the proportion of individuals with a mutation causing a particular disorder who exhibit clinical symptoms of that disorder, most often refers to autosomal dominant conditions

54
Q

define: consanguinity

A

o genetic relatedness between individuals descended from at least one common ancestor
 Decrease in genetic variability

55
Q

define: anticipation

A

o the tendency in certain genetic disorders for individuals in successive generations to present at an earlier age and/or with more severe manifestations; often observed in disorders resulting from the expression of a trinucleotide repeat mutation that tends to increase in size and have a more significant effect when passed from one generation to the next

56
Q

define: genotype

A

the genetic composition

57
Q

define: Mosaicism

A

o within a single individual or tissue, the occurrence of two or more cell lines with different genetic or chromosomal constitutions

  • occurs when a person has two or more genetically different sets of cells in his or her body
58
Q

what is germline mosaicism

A
  • mutation confined to a portion of germ cells (ova or sperm)- can be transmitted to offspring
59
Q

what is somatic mosaicism

A
  • normal and abnormal cell lines within the cells of the body (may or may not include the germline)
  • cannot be transmitted to offspring unless present in germline
60
Q

DESCRIBE RESOURCES AVAILABLE FOR HEALTH CARE PROVIDERS AND PATIENTS WITH GENETIC CONCERNS: Genetic counselors

A

after your initial screening

61
Q

DESCRIBE RESOURCES AVAILABLE FOR HEALTH CARE PROVIDERS AND PATIENTS WITH GENETIC CONCERNS: Newborn screening

A

o Testing done within days of birth to identify infants at increased risk for a specific genetic disorder so that treatment can begin as soon as possible
o when a newborn screening result is positive, further diagnostic testing is usually required to confirm or specify the results and counseling is offered to educate the parents

62
Q

DESCRIBE RESOURCES AVAILABLE FOR HEALTH CARE PROVIDERS AND PATIENTS WITH GENETIC CONCERNS: predictive testing

A

o Testing offered to asymptomatic individuals with a family history of a genetic disorder and a potential risk of eventually developing the disorder

63
Q

DESCRIBE RESOURCES AVAILABLE FOR HEALTH CARE PROVIDERS AND PATIENTS WITH GENETIC CONCERNS: Prenatal diagnosis: (synonym: prenatal testing)

A

o Testing performed during pregnancy to determine if a fetus is affected with a particular disorder.
o Chorionic villus sampling (CVS)
o Amniocentesis
o Periumbilical blood sampling (PUBS)
o Ultrasound
o Fetoscopy are examples of procedures used either to obtain a sample for testing or to evaluate fetal anatomy.

64
Q

DESCRIBE RESOURCES AVAILABLE FOR HEALTH CARE PROVIDERS AND PATIENTS WITH GENETIC CONCERNS: carrier testing

A

o is used to find people who “carry” a change in a gene that is linked to disease.
o Carriers may show no signs of the disease
 However, they have the ability to pass on the gene change to their children, who may develop the disease or become carriers themselves.
o Some diseases require a gene change to be inherited from both parents for the disease to occur.
 This type of testing usually is offered to people who have a family history of a specific inherited disease or who belong to certain ethnic groups that have a higher risk of specific inherited diseases.

**when you have the potential of both of the parents carrying one copy of an autosomal recessive gene mutation and you want to know if the offspring has 25% chance of inheriting that mutation

65
Q

DESCRIBE RESOURCES AVAILABLE FOR HEALTH CARE PROVIDERS AND PATIENTS WITH GENETIC CONCERNS: Pharmacogenetics testing

A

o gives information about how certain medicines are processed by an individual’s body.
 This type of testing can help your provider choose the medicines that work best with your genetic makeup.

**how certain individuals respond to certain medication (i.e. growing rapidly in cancer tx and psychotropic drugs)

66
Q

DESCRIBE RESOURCES AVAILABLE FOR HEALTH CARE PROVIDERS AND PATIENTS WITH GENETIC CONCERNS: Diagnostic testing

A

o Testing designed to confirm or exclude a known or suspected genetic disorder in a symptomatic individual or, prenatally, in a fetus at risk for a certain genetic condition

67
Q

define epigenetic

A

o the study of heritable phenotype changes that do not involve alterations in the DNA sequence
- changes to an organism that are caused by modification of gene expression rather than genetic code itself
- the study of how your behaviors and environment can cause changes that affect the way your genes work
 finding that environment impacts epigenetic area

68
Q

what is epigenetic modifications

A

o Specific environmental or nongenetic factors, such as diet and exposure to certain chemicals, can drive such modifications
 Example alcohol has been shown to affect methylation patterns in animal models, so the harmful effects of fetal alcohol exposure may be mediated through epigenetic mechanisms
o Maternal dietary deficiency during pregnancy may cause epigenetic modification of fetal genes, leading to an increased risk of obesity and diabetes in the offspring later in life
 In some animal models, the insulin-like growth factor 2 gene (IGF2) is a target of these epigenetic modifications

69
Q

what is epigenetic transgenerational inheritance?

A

 hereditary transmission of epigenetic change to successive generations
o Can be reversed

70
Q

Describe one method of epigenetic research

A

o Twin studies
 Compare methylation and other signatures of epigenetic modification in identical (monozygotic) twin pairs, whose DNA sequence are essentially the same
 As twins age, they demonstrate increasing differences in methylation patterns of the DNA sequences of their somatic cells; these changes are reflected in increasing numbers of phenotypic differences
 Twins with significant lifestyle differences (smoking vs non-smoking) accumulated large number of differences in their methylation patterns
 Despite identical DNA sequences, they become more and more different as a result of epigenetic changes, which in turn affect the expression of genes

71
Q

what are the three types of epigenetic modifications?

A
  • DNA methylation: causes genes to become inactive or silent
  • Histone modification: changes in chromatin therefore theres changes the genes dont get expresed
  • mRNa: regulate gene expression mostly at post-translational level
72
Q

what does epigenetic change occur in response to?

A

(gene alteration and not mutation which results in phenotype changes) occur in response to external and internal environmental variations (internal and external influences)

73
Q

what are phenotypic changes cause by?

A

DNA methylation and/or histone modifications which leads to gene expression

74
Q

what can have profound effects on epigenetic and trigger susceptibility to diseases? (10)

A

-Behaviors
-nutrition
-chemicals
-industrial pollutants
-aging
-inflammation
-drugs
-infections
-dysbiosis (microbiome changes)
-ultraviolet exposure

75
Q

what is the risk of acquiring a chronic disease influenced by?

A

environmental cues as well as a person’s genetics

**genetic factors are not the major causes of chronic disease

76
Q

what are genetic disorders caused by?

A

a change (either mutation or alteration) of DNA sequence, consequently its expression

77
Q

the key components to accurate family history to determine genetic risks

A

a. Health problems run in families; family hx may be a risk factor in all phases of life
b. Need to collect at least 3 generations
c. Include info on major medication conditions, causes of death, age at diseases diagnosis, age at death and ethnic background
d. Risk categories based on family hx

78
Q

Risk categories based on family hx: Average risk

A
  1. No affected family members
  2. Only one affected 2nd degree relative from one or both sides of the family
  3. No known family history of disease
  4. Adopted person with unknown family hx
79
Q

Risk categories based on family hx: Moderate risk

A
  1. One 1st degree relative with late or unknown onset of disease
    (i.e. normal or late onset: the development of breast cancer after the age of 60 is a normal onset of that disease and put you at a moderate risk category if you have relative who developed cancer at a later age)
  2. Two 2nd degree relatives from the same side of the family with late or unknown disease onset.
80
Q

Risk categories based on family hx: High risk

A
  1. Early disease in a 1st degree relative (if an individual developed breast cancer prior to the age of 50, particularly in 30s or 40s–they will be considered high risk and so will their relatives)
  2. Early disease in a 2nd degree relative (CAD)
  3. Two affected 1st degree relatives
  4. One 1st degree relatives w late or unknown disease from the same side of the family
  5. Two affected 2nd degree relative with at least one having early onset
  6. 3 or more affected family members
  7. Presence of a “moderate risk” family hx on both sides of the family
81
Q

what is CRISPR

A

allows scientists to make changes to cells to make changes to prevent mutations. A way for scientists to insert or change DNA in cells.

82
Q

benefits of CRISPR

A

there are 7k monogenetic diseases that can be tracked to a single gene with a defect with multiple mutations. CRISPR would be to modify those monogenetic diseases
- Sickle cell anemia, amloyoidosis, cystic fibrosis, beta thalassemia
- Remove immune cells from body, apply CRISPR tech and turn off checkpoints (prevent bod from attacking itself, mimicked by CA cells), put immune cells back in body

83
Q

risk of CRISPR

A

i. Creating incurable disease or potential mutations
ii. Moratorium in US/EU on work on germ lines
iii. Eliminate entire group of ppl with disease and disabilities from society- beliefs about good and bad genes cause discriminatory attitudes
iv. Risk of eugenics by excluding people with disabilities from coming into the world
v. Creating designer babies with ideal traits and characteristics

Advanced Patho Exam 2 (4 decks)

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