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foundations. exam 2 > Genetics > Flashcards

Genetics Flashcards

1
Q

what are genes

A

hereditary units of DNA transmitted from one generation to another, basically they are codes for the production of proteins

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2
Q

what is a Locus

what is an allele

A

the specific location of a gene on a chromosome

alleles are different versions of. a gene

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3
Q

human alleles

A

humans have 2 alleles for each autosomal gene

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4
Q

chromosomes

A

structure composes of genes located in the nucleus of a cell

they are distinguished from each other by length and the position of the centromere

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5
Q

homologous chromosomes

A

have the same genes on the same loci one is maternal and one is paternal

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6
Q

hw many chromosomes do human somatic cells have

A

46 total chromosomes made of 23 pairs

23 from mom23 from dad

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7
Q

mutations

A

can be spontaneous or induced by exposure to mutagenic chemicals or radiation
the effects vary and depend on where in the gene code the mutation has occurred

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8
Q

net result of a mutation

A

can be a physical. appearance or some other trait, again depending on the location

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9
Q

allosome pair

A

the sex chromosome pair, all other 22 pairs are autosome chromomosemes

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10
Q

p arm, r arm

A

in human chromosomes the short are is the p arm and the long arm is the q arm

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11
Q

what determines maleness

A

genetic factors on the Y allosome

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12
Q

mitosis involves which cells

A

somatic, creates an exact copy through division creates two daughter cells

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13
Q

meiosis

A

produced gametes have 23 new chromosome pairs with new combos of the original maternal and paternal copies
only occurs in germ cells in the gonads
consist of two consecutive cell divisions producing cells with half he number diploid to haploid

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14
Q

co dominance example

A

when two alleles for a trait are equally expressed AB blood type
an allele lacks complete dominant and restive relationships and both are observed

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15
Q

incomplete dominance

A

heterozygotes have phenotypes that have both alleles visible as a blend
creates a third phenotype
human ex- wavy hair, skin color

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16
Q

penetrance

A

probability that individuals in a population who have a particular gene combination will show the condition

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17
Q

functions of 3 generation pedigree

A 
Making a diagnosis
— Deciding on testing strategies
— Establishing the pattern of inheritance
— Identifying people at risk
— Educating the patient
— Determining reproductive options
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18
Q

pedigree language

A

male square female circle
Diagonal line through symbol – deceased — Shaded symbol – affected with trait
— Half-shaded symbol – carrier of trait

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19
Q

Consultand

A

The person seeking genetic advice

—Can be healthy or a person with a condition

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20
Q

proband

A

the affected individual

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21
Q

autosomal dominant

A

65% of human monogenic disorders

mutations at just a single allele can cause a disease in an individual

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22
Q

autosomal dominant example

A

Huntington’s disease

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23
Q

characteristics of Autosomal Dominant disorders

A

vertical pattern multiple generations are affected
expressivity may be variable
some with the makeup may not show the phone type
males and females equal
male to male transmission seen

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24
Q

autosomal recessive

A

25% of human monogenic disorders
tend to envolve enzymes or receptors
rare
often seen in consanguinity

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25
Q

autosomal recessive example

A

cystic fibrosis

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26
Q

x linked

A

5% of human monogenic disorders
males more likely to develop both D and R
D and R only apply to females
all daughters of an affected male are heterozygous carriers
males usually more severely affected than females

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27
Q

x linked heterozygous females usually are

A

normal or mild

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28
Q

x linked male to male transfer

A

is not possible

unaffected makes do not transmit the phenotype

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29
Q

x linked dominant examples

A

aport’s syndrome, fragile X syndrome

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30
Q

x linked recessive example

A

wiskott aldrich syndrome

Duchenne muscular dystrophy

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31
Q

Multifactorial/Complex Disease examples

A 
— Cancer
— Diabetes
— Asthma
— Heart disease
— Mental illness
— Cleft lip/cleft palate

need an environmentally factor to turn on gene, meet threshold for phenotype to show

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32
Q

Down syndrome

A

trisomy 21, most common chromosomal abnormally in live births
gamut has two copies of chromosome 21
leads to trisomy when it is fertilized
1 in 500 pregnancies

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33
Q

pre natal testing for Down syndrome

A

quad screen and nuchal translucency

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34
Q

what else can cause Down syndrome

A

4% f cases are due to roberystonian translation, this would require us to do parental chromosome studies

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35
Q

Down syndrome characteristics

A

intellectual disability, facial appearance, 40% cardiac defects 75% hearing loss less than 50% have visual problems and 7% have GI defects

increased social skills in childhood

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36
Q

Edwards syndrome

A

trisomy 18, second most common autosomal trisomy that goes to full term
translocation can cause this disorder
many will die before birth or first month
1:5000 live births
IUGR
highly lethal in utero 85% are lost between week 10 to term
50% die in first week of life
2% 1 year survival rate
heart go and kidney defects

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37
Q

Edwards syndrome characteristics

A

kidney and. heart defects, developmental delays club foot rocker bottom feet
low set ears small jaw

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38
Q

patau syndrome

A 
trisomy 13 
1:16000 live births 
Severe intellectual disability
— Many physical abnormalities
— Cleft lip or palate
— Seizures
— Small jaw
Polydactyly
— Heart defects, brain/spinal cord abnormalities
— Many children die within first days or weeks of life
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39
Q

patau syndrome and translocation

A

Some caused by Robertsonian translocation involving chromosomes 13 and 14
When a part of chromosome 13 gets attached to chromosome 14 during formation of gametes
— Affected people have 2 normal copies of 13 plus an extra copy attached to another chromosome

40
Q

Cri-du-Chat Syndrome

A

chromosomal abnormality deletion of part of short arm on chormose 5
Cat-like cry of affected children due to abnormal larynx development
Intellectual disability, wide set eyes, low ears
1 in 50,000 births
Can be detected in utero with CVS

41
Q

Klinefelter’s Syndrome

A

Extra X chromosome, 47 XXY
Occurs during gametogenesis
— Affects male physical and cognitive development
— Accounts for many first trimester losses
— Physical traits become more apparent after puberty
Most common sex chromosome aneuploidy in males —
Hypogonadism, infertility
— Gynecomastia, reduced hair

42
Q

Turners syndrom

A 
45 X, affects development in females
 Gonadal dysgenesis
— Non-functional ovaries
— Short stature — 
Broad chest
— Webbed neck — 
Amenorrhea — 
Infertility
— Cardiovascular abnormalities
43
Q

Huntington’s Disease

A

A neurodegenerative disease
— Causes uncontrolled movements, emotional problems, and loss of thinking ability, changes in personality
— Early signs: depression, irritability, poor coordination, trouble learning
chorea
—Adult onset: genetic defect is latent for 3-5 decades, then manifests as progressive neuronal dysfunction

44
Q

Huntington’s Disease Pathophysiology

A

HD gene on chromosome 4 that codes for a unique protein called huntingtin
—CAG trinucleotide repeat —
Normal: 10-35 repeats
—In HD: 36-120 repeats
causes microscopic deposits of protein in neurons
Average time from symptom onset to death is 15 years

45
Q

Huntington’s Disease inheritance

A

Only human disorder of complete dominance

Heterozygotes are just as affected clinically as homozygotes

46
Q

Alzheimer’s Disease

A

A neurodegenerative disease
Most common form of dementia in older individuals
Usually begins after age 60; risk increases with age
— Death usually occurs within 10 years
— People with parent, sibling, or child with AD are at increased risk
Progressive mental deterioration: memory loss, confusion,
disorientation

47
Q

dementia forms

A

65% from Alzheimer’s Disease —

35% vascular in nature

48
Q

Alzheimer’s Disease Pathophysiology

A

loss of acetylcholine causes — Formation of plaques and tangles
— Atrophy of brain
— Resultant effect – blocked communication
Several gene mutations cause predisposition to AD

49
Q

Alzheimer’s late vs early onset

A

familial early onset

sporadic late onset

50
Q

early onset

A 
Many members of multiple generations affected
— Symptoms start before age 65
— Mutations on chromosomes 1, 14, or 21
— Induce formation of a “sticky” protein
— Rare - <5% of cases of AD
— Autosomal dominant
51
Q

Sporadic Alzheimer’s Disease

A

One gene has been shown to increase risk
— Chromosome 19 apolipoprotein E (APOE) gene — Not everyone carrying the gene develops disease
— Definitive diagnosis: autopsy-plaques and tangles

52
Q

Hereditary Breast and Ovarian Cancer Syndrome risk factors

A

gender age and family history

up to 10% of breast and ovarian cancers are caused by known predisposing genetic factors

53
Q

Hereditary Breast and Ovarian Cancer Syndrome Genetic testing

A

Preferable to first test an individual who is affected by cancer before testing unaffected family members
— Helps to identify whether a detectable BRCA1 or BRCA2
— An individual can inherit a BRCA1 or BRCA2 mutation yet never develop cancer

54
Q

colorectal cancer

A

Genetic predisposition is the main risk factor in only a small proportion of people
— Diet, exercise, smoking, obesity are stronger risk factors in most people

55
Q

familial colorectal cancers

A

Patterns within a family that exist without identifying a specific mutation
A family history of one or more people with colorectal cancer or premalignant polyps

56
Q

familial colorectal cancers may be due to

A

Chance alone
—Shared exposure to a carcinogen or diet/lifestyle factors
—Combination of gene mutations and environmental risk factors

57
Q

Familial adenomatous polyposis (FAP)

A

autosomal dominat
genetic mutation at APC (adenomatous
polyposis coli) gene
polyps in colon begin forming in adolescence
APC is a tumor suppressor gene on chromosome 5
when it is mutated it allows for cancers to develop in 20s
risk of developing colorectal cancer is near 100% usually before age 50
Time from polyp to cancer development is 10+ years

58
Q

genetic cosseting and testing for FAP

A

should be offered to all patients with suspected diagnosis of FAP after colonoscopy and to relatives at risk
children should have the screening by 10 years of age

59
Q

recommendation for those with established FAP

A

total colectomy before age 20

60
Q

hereditary nonpolyposis colorectal cancer

A

HNPCC / Lynch syndrome
2-3% all colorectal cancers
autosomal dominant
mutation in many genes that code for DNA repair
more rapid transition from adenoma to cancer than FAP
cancers occur earlier 30 and 40s
can occur with small number or no polyps present
associated with formation of other cancers such at uterus ovaries stomach UT small bowl and bile ducts

61
Q

hereditary nonpolyposis colorectal cancer men vs women

A

50% chance of cancer in women and 70% in men

62
Q

genetic testing HNPCC

A

if mutation is found
it is recommended that regular colonoscopy start at age 25 for relatives or 5 years younger than the youngest that those diagnosed
upper endoscopy every two years to screen for gastric cancer
screening for endometrial and vain cancer in women at age 25 to 35

63
Q

chronic myelogenous leukemia

A

myeloproliferative disorder (blood cancer)
more common in men
55 years old median age for presentation
translocation between chromosomes 9 and 22

64
Q

Philadelphia chromosome

A

chromosome 22

produces a protein that codes doe an enzyme that causes too many stem cells to develop into WBCs

65
Q

chronic myelogenous leukemia pathophysiology

A

increased production of abnormal white blood cells that are none functional and take up bone marrow space that is meant for WBC RBC and platelets

66
Q

chronic myelogenous leukemia clinical presentation

A

insidious onset slow progression over months or years

infection anemia bleeding fever night sweat fatigue

67
Q

chronic myelogenous leukemia diagnosis

A

bone marrow aspiration for karyotype

68
Q

hemophilia

A

bleeding disorder cause by mutation in genes that code for coagulations proteins
mutations on F8 or F9 on the X sex chromosome
x linked recessive

69
Q

hemophilia mutations (2)

A

F8 causes VIII deficiency causing the more common hemophilia A
F9 causes IX deficiency causing hemophilia B or Christmas disease

70
Q

hemophilia clinal manifestations

A

hemarthrosis, bleeding into muscle and soft tissue, prolonged bleeding or oozing
severity is variable

71
Q

sickle cell disease pathophysiology

A

atypical hemoglobin molecules (S) distorts red blood cells in to present or sickle shape causing RBC to break down prematurely
the mutation occurs on HBB gene

72
Q

sickle cell disease clinical manifestations

A

anemia, infections, episodic pain, SOB, fatigue delayed growth

73
Q

sickle cell disease

A

autosomal recessive

more common in people whose ancestors came from Greece Africa turkey Italy

74
Q

cystic fibrosis

A 
autosomal recessive 
mutation in the CFTR (regulator) gene 
this gene codes for a protein that regulates chloride channels in epithelial cells 
when it is mutated the protein is defective and there is a disruption in the chloride and water transport and water balance in secretions is disrupted 
common in white population in the US 
1 3500 white newborns 
1 in 25 are carriers 
diagnosed by age 1
75
Q

cystic fibrosis clinical manifestations

A

Causes thick, sticky mucous obstructing airways in lungs and
ducts in pancreas
difficult breathing, infections in lungs

76
Q

cystic fibrosis Problems with nutrient digestion

A

Buildup of mucous prevents pancreatic enzymes from reaching intestine
— Failure to thrive, poor growth rate
— Meconium ileus – newborn intestinal obstruction due to thick
fecal waste products

77
Q

most common morbidity associated with CF

A

pulmonary disease
Pulmonary system can’t defend against pathogens well – leads to sinusitis and bronchitis
— Most common organisms: S. aureus, P. aeruginosa, Aspergillus — Nasal polyps, nosebleeds, chronic sinus infections common in
CF patients
— Thick mucous builds up in lower airways causing obstruction

78
Q

sweat chloride test

A

primary test for CF diagnosis
Defective chloride channel doesn’t allow chloride to be
reabsorbed
— Concentration of chloride in sweat is elevated in CF
— Genetic testing used to confirm results

79
Q

marfans syndrome

A

autosomal dominant
inherited muslin or a new mutation of the fibrillar -1 gene
defects are seen in the connective tissue of bones ligaments muscles blood vessels and heart valves

80
Q

marfans syndrome clinical manifestations

A 
tall stature 
arm span wider than body height 
long narrow face 
high arched palate 
over crowed teeth 
scoliosis 
hyperflexible joints 
chest deformities
81
Q

marfans syndrome key featurs

A

dislocation of the lens of the eye
aortic aneurysm and dissection
heart defects are major causes of morbidity and morality
mitral valve prolapse and aortic valve regulation
= SOB fatigue palpitations

82
Q

those with marfans should avoid contact with

A

sports caffeine and decongestants due to increased stress placed on CV system

83
Q

Neurofibromatosis Type I

A

— Von Recklinghausen disease, autosomal dominant
mutation on NF1 gne on chromosome 17, most common
a tumor suppressor gene
results in growth of neurofibromas and skin pigmentation changes cafe au last spots
lisch nodules in iris
freckles in axillae and groin

84
Q

neurofibromas

A

benign tumors that grow on nerves of skin and brain

2 or more for diagnosis of Neurofibromatosis Type I

85
Q

Crowe sign

A

axillary or inguinal frecking

86
Q

neurofibromas diagnostic features

A

1.5 cm or larger café-au-lait spot post puberty or 6 or more café-au-lait spots 0.5 cm or larger in before puberty
— 2 or more neurofibromas
— Axillary or inguinal freckling (Crowe sign)
— Optic glioma
— 2 or more Lisch nodules
— 1st degree relative with NF1

87
Q

polycystic kidney disease

A

Clusters of fluid filled sacs develop in kidneys, this affects ability to filter the blood properly. kidneys become enlarged and can fail

88
Q

polycystic kidney disease clinical manifestations

A

hypertension, back pain, hematuria, UTIS kidney stones

89
Q

polycystic kidney disease other associations

A

liver cysts, heart valve abnormalities, increased aortic aneurysm and brain aneurysm

90
Q

polycystic kidney disease forms

A

Autosomal dominant – sx start in adulthood — 1 in 1000; PKD1 and PKD2 genes
— Usually inherited (90% of the time)
— Autosomal recessive – rare, lethal early in life — 1 in 30,000
— PKHD1 gene

91
Q

Approximately _____% of all newborns have some birth defect

A

10%
Ranges from minor biochemical problem to severe physical deformity
Caused by variety of biological, chemical, and physical agents
— Contributors: mutant genes, chromosomal defects, multifactorial components

92
Q

biggest cause of birth defects

A

unknown etiology

93
Q

Teratology

A

study of abnormal development

94
Q

Teratogens

A

nything capable of disrupting embryonic or

fetal development and producing malformations

95
Q

critical period for

A

teratogenic effects is 3-16 weeks

timing of exposure determines which systems are affected

96
Q

CNS development vs teeth and palate development in utero

A

CNS begins to develop in 3rd week, while teeth and palate begin to form in 6th-7th week

97
Q

new born screening

A

Biochemical analysis that determines whether certain proteins (enzymes) are present or absent
— typically autosomal recessive conditions
— “inborn errors of metabolism”
— Inherited defect in one or more enzymes
law 2008 increased uniform testing
first test at 24-36 hours old next at 5 to 10 days

foundations. exam 2 (10 decks)

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